Leaving central heating on 24/7 and boiler short-cycling

heavydawson

My wife and I just moved into a new build at the start of November and I've been slightly disappointed with the heat performance. The spec of the house is as follows:

• 150mm Cavity Wall
• 150mm Full Fill Solid Cavitytherm Insulation (Paper u-value of 0.12)
• Triple Glazed windows and doors throughout
• Draught lobby for front door
• Airtightness tapes and membranes applied
• HRV installed
• 340mm Rock Wall between and over joists in attic
• Airtight Attic Hatch
• 165mm Underfloor insulation
• 2 course Quinnlite foundation blocks where UF insulation meets wall bases
• Wrapped Hollowcore First Floor
• Condensing Boiler and Radiators for heating. Radiators appear to be sized correctly for rooms (I checked the plumbers BTU req. calcs independently and he was correct including over-sizing the north facing rads capacity)

So we had the heating come on two times a day for an hour in the morning and an hour in the evening. I'd like to keep the house to the recommended guidelines of 21 for living areas and 16 or so for bedrooms. Kitchen and living room are south-facing and joined by a set of internal sliding doors. We have a stove with an external air supply which we lit that did a great job of bringing the room up to temperature.

After reading online that houses that are thermally massive like ours benefit more from continuous heating, I tried leaving the heat on for an extended period of time yesterday. So I ran it from 2pm to roughly 11pm. At the beginning the boiler thermostat was set to roughly 72.5 degrees, but around 6pm I dropped that to 65 (The range is 65-75).

I took some temperature measurements in different parts of the house at 11pm last night and 11am today.

Room 11pm 11am Notes
Study 21C 19.5C North-east part of house- no direct sunlight
Kitchen 22.8C 21.5C South facing. Lots of glazing
Master Bed 18.6C 19.5C South facing. Heating came on for 1 hour from 8.30 to 9.30am

I'm much happier with the current temperature and apparent heat retention of the house, but I do have some questions.

* It appears the principles of thermal massing are in action here, so I'm wondering if I should now leave the heat on some extended running period of time? My system controls are zoned for upstairs, downstairs and hot water. Three times can be set for each zone Mon-Fri and a separate set of three times can be set for Sat+Sun

* The hot water isn't as warm as we feel it should be when the boiler stat is set to 65, so we'll up that gradually until it's ok. We're also installing solar panels shortly.

* I'm worried about the boiler short-cycling with the new heating regime. I have a security camera beside it and the tank and I was watching it around 9pm last night. It would come on for a minute, then off for 5 minutes, then on again, and so on. I'm now wondering if the boiler is over-sized for the house? The heat output with the current factory default nozzle is 42.5kw. Giving that we appear to be dropping a degree and half over 12 hours with an external air temp of 4 degrees, is there anyway of working out what the boiler sizing based on heat demand should be? The nozzle can be swapped out to give a lower output of 36kw, but anything less means replacing the boiler with lower output.

* There's 4 pumps in our plant room - One each for US, DS, HW and solid fuel stove. The pumps are all SurePump 55/130. I've read a bit about modulating pumps and I'm wondering if they're also worth installing? Particularly the stove pump because we've found even with the stove blowing out heat, the rads are never warm, and I'm just wondering if the fixed speed of the existing pump is too fast for the rads to really build up heat?

* The US room stat is in our master bedroom which I'm happy with, but the DS stat is in the hall, and given that's such a huge space, I think it would be better off in the study just off the hall. I work from home 2 days a week in there, and so I'm thinking it should be considered a living space. Also, it gets no direct sunlight most of the year, so it's far less prone to temperature fluctuations. It would just involve moving the site literally in situ from one side of the wall to the other. Small job worth doing?


Sorry for long post, but the little experiment yesterday has got me wondering if the whole hour in the morning, hour in the evening regime is the right way to heat the house, and I just want someone to maybe talk me through it, particularly if they have gone through something similar?

MicktheMan

OP,
based on your spec I would definitely run the heating regime such that the house does not cool down.
I live in a mid 70's built thermally massive house, standard ofch boiler and rads, 3 independent zones (dhw, living area and bedrooms). Air tightness is okay at 3m3/hr/m2. Ventilation by mvhr.
The space temperature is controlled by two "control mechanisms"
1. Boiler control: I have the boiler output set to its lowest (nozzle size/oil pressure) but boiler water temperature set at 75. In addition I have a pipe stat installed on the return to the boiler which knocks the burner off when the return temp rises above various temperatures depending on the external conditions ( a sort of manual external temperature compensator). These various temperature settings have been determined by trial and error. So when it is mild out the return pipe setpoint is set lower than when it is cold out. I also have an hour meter on the boiler to be able to monitor the length of time the boiler is burning oil. Finally, dhw zone overrides the pipestat so dhw is always hot (timed to heat the water each morning for an hour only). The boiler doesn't cycle (except sometimes during the dhw heating hour)
2. Internal space controller: Per heating zone, a digital chronostat (time/temperature control in one unit) allows different temp setpoints for different times of the day. The location of these are very important. These have been programmed once and generally are never touched except to change the batteries annually. Heating is "on" from 6am to midnight. Internal temperature fluctuation is around 2 degrees (18-20 degC). The house is never cold (always feels warm) and oil burn hours per day is between 3 and 4.5 depending on how cold it is (including hot water). These chronostats are turned off generally from April to October. The rads are never roasting (as they don't need to be to keep the house at temp)

From what you write, you might benefit greatly from a similar setup.
PM me if you want to discuss the finer points.

Froststop

heavydawson wrote: »

After reading online that houses that are thermally massive like ours benefit more from continuous heating, I tried leaving the heat on for an extended period of time yesterday. So I ran it from 2pm to roughly 11pm. At the beginning the boiler thermostat was set to roughly 72.5 degrees, but around 6pm I dropped that to 65 (The range is 65-75).

I took some temperature measurements in different parts of the house at 11pm last night and 11am today.

Room 11pm 11am Notes
Study 21C 19.5C North-east part of house- no direct sunlight
Kitchen 22.8C 21.5C South facing. Lots of glazing
Master Bed 18.6C 19.5C South facing. Heating came on for 1 hour from 8.30 to 9.30am

18-20 would be standard.

heavydawson wrote: »

I'm much happier with the current temperature and apparent heat retention of the house, but I do have some questions.

* It appears the principles of thermal massing are in action here, so I'm wondering if I should now leave the heat on some extended running period of time? My system controls are zoned for upstairs, downstairs and hot water. Three times can be set for each zone Mon-Fri and a separate set of three times can be set for Sat+Sun

What Temps are the room stat set to? If the room temp is higher the rads on that zone won't operate.

heavydawson wrote: »

* The hot water isn't as warm as we feel it should be when the boiler stat is set to 65, so we'll up that gradually until it's ok. We're also installing solar panels shortly.

Try to avoid turning up temp, if you have a zone valve on the hot water circuit it may be controlled by a temp stat on the cylinder. If the stat is at 60-65 you may only have a circulation problem.

heavydawson wrote: »

* I'm worried about the boiler short-cycling with the new heating regime. I have a security camera beside it and the tank and I was watching it around 9pm last night. It would come on for a minute, then off for 5 minutes, then on again, and so on. I'm now wondering if the boiler is over-sized for the house? The heat output with the current factory default nozzle is 42.5kw. Giving that we appear to be dropping a degree and half over 12 hours with an external air temp of 4 degrees, is there anyway of working out what the boiler sizing based on heat demand should be?

If the boiler is turned on and none of the room stats require heat, it will operate on it's own temp stat. for a rough idea regarding boiler sizing, multiply the number of rads by an average of 5000 BtU. 1.5 degrees of a drop over 12 hrs, I would think would be quit good when the heating is off.

heavydawson wrote: »

* There's 4 pumps in our plant room - One each for US, DS, HW and solid fuel stove. The pumps are all SurePump 55/130. I've read a bit about modulating pumps and I'm wondering if they're also worth installing? Particularly the stove pump because we've found even with the stove blowing out heat, the rads are never warm, and I'm just wondering if the fixed speed of the existing pump is too fast for the rads to really build up heat?

The stove may not have the output to heat the rads and hot water.

heavydawson wrote: »

* The US room stat is in our master bedroom which I'm happy with, but the DS stat is in the hall, and given that's such a huge space, I think it would be better off in the study just off the hall. I work from home 2 days a week in there, and so I'm thinking it should be considered a living space. Also, it gets no direct sunlight most of the year, so it's far less prone to temperature fluctuations. It would just involve moving the site literally in situ from one side of the wall to the other. Small job worth doing?

Personal choice, moving could mean the hall will always feel cold.

heavydawson wrote: »

Sorry for long post, but the little experiment yesterday has got me wondering if the whole hour in the morning, hour in the evening regime is the right way to heat the house, and I just want someone to maybe talk me through it, particularly if they have gone through something similar?

Judging from your post, the house is quite large. If you can get those temps for 2 hrs running time a day your doing quite good.

heavydawson

Thanks Froststop.
The measurements I took were after the continuous heating period, and I've reduced the the length of time we're heating since then. While not quite back to the 1 hour in the morning, 1 in the evening, I'm now looking at maybe an 1 hour in the morning upstairs and down (previously was upstairs only). These keeps the kitchen above 21 all day. I've now set the room stat in the master bedroom to 18 and this comes on once in the morning and evening and seems to be keeping that room hovering around the 18 mark pretty much all day.

Re. DHW temp. We have a zone valve and cylinder stat (set to 65C).

The downstairs stat is trickier. As I said, it's in the hall, and I'm setting it based on the temperature in the study where I work from home, which I'm keeping between 20-21 during the day. To do this, I've found I need to set the hall stat at 15 degrees, and even at that.
I'm happier now that the temperature has stabilized to what we'd like it to be, but my attention is now focussed on optimizing the boiler. In our efforts to get the rooms up to temp with the original 2 hours per day regime, we upped the boiler stat, and had all the control valves on every rad opened to the last (Didn't touch the lock-shields). The boiler manual recommends a rad flow of 70 and return of 50, but I'm pretty sure we're probably 70/69 :-)
I want to get the a pair of pipe stats and go to each rad to get the return right, and once that's done, see if I can get away with reducing the nozzle size on the boiler to reduce the oil consumption.

Re, the stove - yup, quite possible. TBH, I'm not too bother if it's mostly contributing to hot water, as long as it's contributing. :-)

I'd love to know more about weather compensating controls if anyone else is reading? Not sure if it's possible to install one at this stage as the boiler is in the garage and the controls are in the house, but interested to hear of people experiences. I've seen some interesting debates as to whether or not they're need in a thermally massive house because the temperature fluctuations are quite low already. All ears for any other tips!

Froststop

heavydawson wrote: »

Thanks Froststop.
The boiler manual recommends a rad flow of 70 and return of 50, but I'm pretty sure we're probably 70/69 :-)
I want to get the a pair of pipe stats and go to each rad to get the return right, and once that's done, see if I can get away with reducing the nozzle size on the boiler to reduce the oil consumption.

I wouldn't worry to much about the return temps at the rads as it will depend on running times and room temp. The return to the boiler would be more important, however it will also depend on the running time and room temps.

The boiler nozzle change may result in having to run the boiler for long to achieve the same result which may not be worth trying.

I wouldn't rely on pipe stats as they can be out by a mile. Came across one lately on a stove which was out by 36 degrees, resulting in the pump not switching on until the pipe was at 76 while the stat was at 40. Could have been a problem if the installer set it at a higher temp.

heavydawson

Froststop wrote: »

I wouldn't worry to much about the return temps at the rads as it will depend on running times and room temp. The return to the boiler would be more important, however it will also depend on the running time and room temps.

The boiler nozzle change may result in having to run the boiler for long to achieve the same result which may not be worth trying.

I wouldn't rely on pipe stats as they can be out by a mile. Came across one lately on a stove which was out by 36 degrees, resulting in the pump not switching on until the pipe was at 76 while the stat was at 40. Could have been a problem if the installer set it at a higher temp.

Correct me if I'm wrong, but isn't the return from the rads the same as the return to the boiler? Granted the return to the boiler might be slightly slower than the rad return, but aren't they one and the same thing?

Froststop

heavydawson wrote: »

Correct me if I'm wrong, but isn't the return from the rads the same as the return to the boiler? Granted the return to the boiler might be slightly slower than the rad return, but aren't they one and the same thing?

Yes but you can't control the temp of the return without changing the flow temp, it's depends room temp, heat loss, system size etc. You would need mixing valves and temp controllers fitted to the system which would only allow a set temp to each circuit and then the return temp will still depend on the above.

heavydawson

Froststop wrote: »

Yes but you can't control the temp of the return without changing the flow temp, it's depends room temp, heat loss, system size etc. You would need mixing valves and temp controllers fitted to the system which would only allow a set temp to each circuit and then the return temp will still depend on the above.

Yup, but I guess that's what I meant by balancing the rads above. The flow temp should be 70C, and the ideal return temp would be 50C. With pipe stats, surely this is something that can be achieved on a rad-to-rad basis, and as a consequence, the boiler return should be predictable? As I understand it, by fixing the flow and return, you're fixing the heat output of the rad (once the system is up to temp). The room temperature shouldn't affect the rad output unless it's using TRVs (only the rads in our living room that has a stove have TRVs).
I can see where trying to get the flow temp spot on to 70C for all rads is tricky, but surely that's just a matter of:
1. Setting the boiler temp correctly
2. Appropriate rad balancing

Froststop

heavydawson wrote: »

Yup, but I guess that's what I meant by balancing the rads above. The flow temp should be 70C, and the ideal return temp would be 50C. With pipe stats, surely this is something that can be achieved on a rad-to-rad basis, and as a consequence, the boiler return should be predictable? As I understand it, by fixing the flow and return, you're fixing the heat output of the rad (once the system is up to temp). The room temperature shouldn't affect the rad output unless it's using TRVs (only the rads in our living room that has a stove have TRVs).
I can see where trying to get the flow temp spot on to 70C for all rads is tricky, but surely that's just a matter of:
1. Setting the boiler temp correctly
2. Appropriate rad balancing

I understand your trying to get the best from your system.

We would usually only balance the rads for even circulation. i.e if a number of the rads are not heating correctly we would open their lockshields and close down some of the better rads to try and get a more even flow through the system. If you upset these you may end up with rads not working at all. In the event of all rads working when the system is commissioned we would not even balance the rads. I would usually run a system first time with all lockshield valves open full and if some rads are slow or not heating I would start by shutting down the hotter ones to even the flow to the rads which are not.

heavydawson

Froststop wrote: »

I understand your trying to get the best from your system.

We would usually only balance the rads for even circulation. i.e if a number of the rads are not heating correctly we would open their lockshields and close down some of the better rads to try and get a more even flow through the system. If you upset these you may end up with rads not working at all. In the event of all rads working when the system is commissioned we would not even balance the rads. I would usually run a system first time with all lockshield valves open full and if some rads are slow or not heating I would start by shutting down the hotter ones to even the flow to the rads which are not.

Interesting, but what about optimizing the boiler efficiency then? If the return is too high, the boiler might not be condensing (so you might be missing <= 10% efficiency). I'm guessing it will still be below the set boiler temp so it will fire anyway? So why not have it firing in condensing mode with a lower return than non-condensing with a higher return? Sorry for the barrage of questions, but I'm curious to know why there seems to be differences of opinion on the matter. Surely I'm better off having the boiler working to the manufacturers recommendations? (70C in, 50C out)?
I realize that might cause longer burn times because the rad output isn't blasting heat, but it will surely decrease the boiler cycles?

Froststop

heavydawson wrote: »

Interesting, but what about optimizing the boiler efficiency then? If the return is too high, the boiler might not be condensing (so you might be missing <= 10% efficiency). I'm guessing it will still be below the set boiler temp so it will fire anyway? So why not have it firing in condensing mode with a lower return than non-condensing with a higher return? Sorry for the barrage of questions, but I'm curious to know why there seems to be differences of opinion on the matter. Surely I'm better off having the boiler working to the manufacturers recommendations? (70C in, 50C out)?
I realize that might cause longer burn times because the rad output isn't blasting heat, but it will surely decrease the boiler cycles?

You can control the return temp at the headers by getting the pumps to switch off. The problem I see is if the return is up to the set point before the room temp, you may not reach the room temp set point on your zones, same for hot water.

There can be alot of different opinions out there. IMO the faster you get up to temp the better, it's a matter of maintaining it after. Another can be to run boiler at lower temps for longer periods can be more efficient on oil. However the cheapest way is not to have it running at all which can be done also.

heavydawson

Froststop wrote: »

You can control the return temp at the headers by getting the pumps to switch off. The problem I see is if the return is up to the set point before the room temp, you may not reach the room temp set point on your zones, same for hot water.

There can be alot of different opinions out there. IMO the faster you get up to temp the better, it's a matter of maintaining it after. Another can be to run boiler at lower temps for longer periods can be more efficient on oil. However the cheapest way is not to have it running at all which can be done also.

I'm following you. You've latched on to something else you might be able to help me out with. What determines whether the pumps are circulating, versus whether the burner is on?
The order of control in my mind is:

IF HEATING ON VIA TIMER
+ ROOM STAT INDICATES HEAT REQUIRED:
-> THEN TURN ON PUMPS AND BOILER (but don't necessarily burn).

I imagine the room and cylinder stats really practically are only controlling the circulating pumps. FWIW we're using a Systemlink Spirozone + SystemLex configuration with seperate NRVs for each zone
But what determines when the boiler actually fires? Is it a stat on the flow from the boiler or the return to the boiler?

heavydawson

Nevermind - found this:
http://www.boards.ie/vbulletin/showpost.php?p=81680727&postcount=3

Froststop

heavydawson wrote: »

Nevermind - found this:
http://www.boards.ie/vbulletin/showpost.php?p=81680727&postcount=3

All depends how it's wired

heavydawson

Thanks for all the pointers froststop, I've another question for you.

Lets say I did set the rad returns to all be 70C flow and 50C return, the base return might still be above 50C, is that correct?
By base return I mean what's left in the flow pipe after all rads have got sufficient flow? As I understand it, the all rads are fed from a common flow and return via a common return.
The common return begins where the common flow ends, is that correct? They're one and the same pipe, just looping back on one another?

So if the boiler is supplying hot water at 70C to the flow, and all rads are receiving 70C, then the common return is also likely starting at 70C before having incremental amounts of 50C return from each rad added to it.

Froststop

heavydawson wrote: »

Thanks for all the pointers froststop, I've another question for you.

Lets say I did set the rad returns to all be 70C flow and 50C return, the base return might still be above 50C, is that correct?
By base return I mean what's left in the flow pipe after all rads have got sufficient flow? As I understand it, the all rads are fed from a common flow and return via a common return.

All water which is pumped out the flow has to return by passing through a rad. If you shut the return valves too much up putting the pump under stress as it may be pumping against a restricted head. i.e if you close/turn off all rads it's the same as the zone valve closing (no circulation)

heavydawson wrote: »

The common return begins where the common flow ends, is that correct? They're one and the same pipe, just looping back on one another?

No, The flow is not linked to the return, only through the rads. I think this is where we're getting confused. The flow splits to each rad, when you get to the end of the line, it connects directly to the last rad. Same for the return on the way back to the header/boiler. If the F&R were linked it would cause a short circuit resulting in problems with circulating/rads heating as water takes it's easiest route.

heavydawson wrote: »

So if the boiler is supplying hot water at 70C to the flow, and all rads are receiving 70C, then the common return is also likely starting at 70C before having incremental amounts of 50C return from each rad added to it.

Maybe in the case of using headers for rad circuits. i.e if each rad has it's own F&R from a header. But all water entering any return will be less the heat loss from the rad.

Froststop

Don't forget to update us on what you have done/decided to do!

heavydawson

Froststop wrote: »

Don't forget to update us on what you have done/decided to do!

TLDR;
2 hours hot water a day, 3 hours CH

Well Froststop, after a little bit of further tinkering, the following regime seems to work pretty effectively:

Monday-Friday
Hot water - 5am - 6am / 5pm-6pm
U/S + D/S CH - 6am - 7am / 5pm-6pm
D/S Only 8pm-9pm
U/S Only 9pm-10pm

Slight variation in timing at the weekend, but the same number of hours for each zone.

Initially I was keen to to run all of the zones at the same time, but we found that the DHW would not get up to temperature when run at the same time as the CH. Once we separated the times, everything was fine again. Not sure if this is a boiler sizing issue or something else, but as long as it can be worked around, I think I'm ok with it.

This is all with the boiler stat set at roughly 72/73C. So next I'm going to start dropping that a little nudge a day until the missus starts complaining :-)

I can't tell you yet how long the boiler fires for during the "ON" heating period, so I'm hoping to set up an hour meter to figure that out roughly.
I'm also getting some pipe stats to properly balance the rads.

Froststop

heavydawson wrote: »

TLDR;
2 hours hot water a day, 3 hours CH

Well Froststop, after a little bit of further tinkering, the following regime seems to work pretty effectively:

Monday-Friday
Hot water - 5am - 6am / 5pm-6pm
U/S + D/S CH - 6am - 7am / 5pm-6pm
D/S Only 8pm-9pm
U/S Only 9pm-10pm

Slight variation in timing at the weekend, but the same number of hours for each zone.

heavydawson wrote: »

Initially I was keen to to run all of the zones at the same time, but we found that the DHW would not get up to temperature when run at the same time as the CH. Once we separated the times, everything was fine again. Not sure if this is a boiler sizing issue or something else, but as long as it can be worked around, I think I'm ok with it.

We would normally size boiler to do everything. You may be undersized, have a circulation problem or just the running time is too short to heat the hot water. If the running times you posted work and your happy, then your on the ball.

heavydawson wrote: »

This is all with the boiler stat set at roughly 72/73C. So next I'm going to start dropping that a little nudge a day until the missus starts complaining :-)

If you can get it down to 65 you will be better off, 70+ is a little too high IMO. If you have a sealed system then I find that when the temp is over 65 then problems with air seem to occur. If 65 is not heating the rooms etc then you may need to add a little to the running times.

heavydawson wrote: »

I can't tell you yet how long the boiler fires for during the "ON" heating period, so I'm hoping to set up an hour meter to figure that out roughly.
I'm also getting some pipe stats to properly balance the rads.

Make sure it's cutting in and out on it's own temp stat. If it runs constantly then your undersized.
Am I correct in saying you have a header system with pumps on each zone? Have you zone valves fitted also? How are they controlled? I presume room stats.

heavydawson

Well the running time we currently have it on is the same as it was before when it ran at the same time as the CH (1 hour). So probably a circulation problem or under-sizing. Like I say, once the DHW and CW are split time-wise, it's all good, so not sure if I'm hugely bothered by it.

Re. the boiler temp, I'm 100% with you. Would much rather have it as low as possible to the point where the missus doesn't miss it. She has an unusually high heat tolerance :-) I can't take a shower at the temperate she does. Always have to turn it down at the shower controls.
That said, 65 is the lowest setting on the boiler. I imagine I'll drop to 70 and see what happens there, then drop another degree, etc. Funny you should mention about the air, I have noticed some of the rads upstairs are partially air-locked and I've bled them twice already.

Not sure what you mean by header system but yes, there are pumps on each zone, and if by valves you mean non-return values, then yes, they're fitted.

There are 4 zones controlled as follows
1. U/S CH - Room stat in master bedroom
2. D/S CH - Room stat in hall
3. DHW - Cylinder stat @ 65
4. Stove D/S - Back boiler with temp stat @ 55C (I believe)

So 4 pumps with a stat each as well as the boiler stat. Boiler is in garage.

Froststop

heavydawson wrote: »

Funny you should mention about the air, I have noticed some of the rads upstairs are partially air-locked and I've bled them twice already.

Yes, this is because the temp is too high, it should improve as you turn it down.

heavydawson wrote: »

Not sure what you mean by header system but yes, there are pumps on each zone, and if by valves you mean non-return values, then yes, they're fitted.

There are 4 zones controlled as follows
1. U/S CH - Room stat in master bedroom
2. D/S CH - Room stat in hall
3. DHW - Cylinder stat @ 65
4. Stove D/S - Back boiler with temp stat @ 55C (I believe)

So 4 pumps with a stat each as well as the boiler stat. Boiler is in garage.

A zone valve is an electrical motorized valve which can be operated by a room stat.
https://www.google.ie/search?q=heating+zone+valve&espv=210&es_sm=122&tbm=isch&tbo=u&source=univ&sa=X&ei=ZODTUtHuIYuUhQev_ICABA&ved=0CGcQsAQ&biw=1600&bih=775

I'm trying to determine if you have any zone valves, by the sounds of it your controlling the pumps for each zone with the room stats and you have no zone valves fitted.
How are you proposing to control/wire the pipe stats?, I presume when the return pipe reaches the set point of the pipe stat, it will shut off the pump for same zone. Is this correct?

heavydawson

Here's a photo of the setup:


You can see the systemlink spirozone between the pumps. From the documentation for it online:

SpiroZone is an inexpensive and simple alternative to valve controlled zoning methods.

, so I'm assuming there's no zone valves and this has taken their place.

The pipe stats I was referring to were just clip on thermometers for balancing the rads. Sorry, not really stats at all.

Froststop

heavydawson wrote: »

The pipe stats I was referring to were just clip on thermometers for balancing the rads. Sorry, not really stats at all.

I have not come across them. Have you info on them?

heavydawson

Froststop wrote: »

I have not come across them. Have you info on them?

Haven't got them yet, but here's what they look like:
https://www.google.ie/search?q=pipe+thermometer&espv=210&es_sm=93&tbm=isch&tbo=u&source=univ&sa=X&ei=7GTUUqDZI_OA7QbQ9YGwAw&ved=0CFUQsAQ&biw=2560&bih=1339

Froststop

heavydawson wrote: »

Haven't got them yet, but here's what they look like:
https://www.google.ie/search?q=pipe+thermometer&espv=210&es_sm=93&tbm=isch&tbo=u&source=univ&sa=X&ei=7GTUUqDZI_OA7QbQ9YGwAw&ved=0CFUQsAQ&biw=2560&bih=1339

Let me know how it works out. I have seen them, I thought there might be a new typ out.

You can also get digital types which may do the job. You seem to be a perfectionist, this might be more accurate.

Ebay (Cheap for the price you could get a few): just tape the probe to the pipe using foil tape to get a better heat transfer.
http://www.ebay.ie/itm/External-Digital-LCD-Thermometer-Temperature-Sensor-Aquarium-Refrigerator-/261357113442?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3cda191062

heavydawson

Froststop wrote: »

Let me know how it works out. I have seen them, I thought there might be a new typ out.

You can also get digital types which may do the job. You seem to be a perfectionist, this might be more accurate.

Ebay (Cheap for the price you could get a few): just tape the probe to the pipe using foil tape to get a better heat transfer.
http://www.ebay.ie/itm/External-Digital-LCD-Thermometer-Temperature-Sensor-Aquarium-Refrigerator-/261357113442?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3cda191062

Nice! Thanks for the tip. The digital thermometers can be hit an miss. I bought 3 when we moved in. Two smaller temp only ones from the one manufacturer and another larger temp+humidity+time model from a different manufacturer. They all showed a different temp when placed side by side in the same room :-)
I suppose they were within their tolerances of +/- 1 degree, to be fair.

Dropped the boiler stat to 65 before the evening heating cycle kicked in. Still loads of hot water, and even though it was freezing here last night, the upstairs heating stat didn't call for heat for 30 minutes after the heating schedule kicked in upstairs this morning.
Think I'm largely done with mucking around with the boiler stat now. Next step is balancing the rads. Really need to get some temperature logging in place around the house as well so I can graph the heat response in front versus back and up versus down,etc.

FWIW froststop, there's some fantastic new thermal imaging tools on the way at relatively affordable prices. I'll probably lay my hands on one to check heat loss in the attic and external walls.
http://www1.flircs.com/flirone/
http://www.muoptics.com/

heavydawson

Had an interesting email conversation with Grant re. the boiler thermostat. Even though the manual says the range is 65-75C, grant replied to me to tell me that the range is actually 55-70C! Theyr'e in the process of updating the manuals to reflect this apparently.
This has a pretty significant bearing on the cylinder stat I would think insofar as setting the boiler stat at the middle of the dial appears to be 62.5C, which mean s the cylinder never gets to temperature if the cylinder stat is 65!
Also in the Grant manual it suggests that radiator systems should have the flow set to 70C and balance the rads to achieve a return of 50C. This would suggest turning the boiler thermostat up all the way to get the correct flow.
Is it just me or does all the above seem odd?

Froststop

heavydawson wrote: »

Had an interesting email conversation with Grant re. the boiler thermostat. Even though the manual says the range is 65-75C, grant replied to me to tell me that the range is actually 55-70C! Theyr'e in the process of updating the manuals to reflect this apparently.
This has a pretty significant bearing on the cylinder stat I would think insofar as setting the boiler stat at the middle of the dial appears to be 62.5C, which mean s the cylinder never gets to temperature if the cylinder stat is 65!
Also in the Grant manual it suggests that radiator systems should have the flow set to 70C and balance the rads to achieve a return of 50C. This would suggest turning the boiler thermostat up all the way to get the correct flow.
Is it just me or does all the above seem odd?

Get an accurate temp sensor and probe. set the boiler to 65 using the temp probe on the flow pipe. See what the boiler stat is set at to get 65 on the flow pipe. Work from there then. However I still think 70+ is too high.

heavydawson

Froststop wrote: »

Get an accurate temp sensor and probe. set the boiler to 65 using the temp probe on the flow pipe. See what the boiler stat is set at to get 65 on the flow pipe. Work from there then. However I still think 70+ is too high.

Good point froststop. I suppose practically what I'm looking for is a Delta-T of 20 across the rads, rather than a straight 70/50 absolute value. Ordering a set of 4 pipe thermometers today. Two for permanent fixture to the boiler flow and return, and two for balancing rads.

shane0007

heavydawson wrote: »

Had an interesting email conversation with Grant re. the boiler thermostat. Even though the manual says the range is 65-75C, grant replied to me to tell me that the range is actually 55-70C! Theyr'e in the process of updating the manuals to reflect this apparently.
This has a pretty significant bearing on the cylinder stat I would think insofar as setting the boiler stat at the middle of the dial appears to be 62.5C, which mean s the cylinder never gets to temperature if the cylinder stat is 65!
Also in the Grant manual it suggests that radiator systems should have the flow set to 70C and balance the rads to achieve a return of 50C. This would suggest turning the boiler thermostat up all the way to get the correct flow.
Is it just me or does all the above seem odd?

The reason for this is to stop homeowners from fiddling with the stat & this is supposed to set at the commissioning stage & explained to the homeowner on handover.
Old type stats can be set as low as 30C. If you set a condensing boiler at below 50C you will destroy the boiler over time.
Hence, the 55C minimum setting +/-5C.

So, at your next service ask the engineer to commission the boiler to suit the installation.