changing from ufh to Rads

Ah Here

shane0007 wrote: »

Not necessarily as if the zones are satisfied, there will be little draw from the 70C loop & the boiler will be constantly on top of the demand, leading to constant short cycling of the boiler. This is the worst condition for a condensing boiler, especially a Firebird.

IMO, the system seems to be ok. The controls are terrible.
Two options:
1. Upgrade the controls completely to something such as the Heatmiser as they are better for UFH as they are not on/off controls as such, but rather a desired temperature during a timed period. Add motorised valves to each manifold & dhw circuits. Timed control for the HW can be done through one of the Heatmiser PRT-HW stats, usually in the kitchen.
2. All of 1. but also add in a small buffer tank/thermal store. The boiler will heat the buffer but called in via a Resol TT1. This allows 2no call points so if buffer falls below 40C, boiler will fire & switches off once 70C is reached. HW circuit would be via a 3 port diverted valve bypassing the buffer. Buffer only feeds the UFH.
Timed controlled UFH with temperature determined time periods rather than on/off periods works far better & more economical.

That's my opinion anyhow.

Do i understand from that that u think the heating shouldnt be on constant?

shane0007

Ah Here wrote: »

Do i understand from that that u think the heating shouldnt be on constant?

Yes. With Heatmiser's stat or a similar one, you set the time zone, example 8pm - 11pm as 19C, then you set 11pm - 7am as 16 or 17C and so on. The UFH is not off as such but rather the stat is satisfied more often.
It can lead to enormous savings. The other advantage you have is that you have Easiscreed. Easiscreed heats up much faster than normal concrete mixes so it will be more suitable to this type of control as it will achieve temperature much faster. It looses much faster also but with the temperature only reduces it will not be too far off.

Ah Here

shane0007 wrote: »

Yes. With Heatmiser's stat or a similar one, you set the time zone, example 8pm - 11pm as 19C, then you set 11pm - 7am as 16 or 17C and so on. The UFH is not off as such but rather the stat is satisfied more often.
It can lead to enormous savings. The other advantage you have is that you have Easiscreed. Easiscreed heats up much faster than normal concrete mixes so it will be more suitable to this type of control as it will achieve temperature much faster. It looses much faster also but with the temperature only reduces it will not be too far off.

I only have easycreed upstaors not downstairs

shane0007

Ah Here wrote: »

I only have easycreed upstaors not downstairs

That won't be a problem. Easiscreed is more suitable for upstairs anyhow as bedrooms require less reaction time. Downstairs is better with more thermal mass.

As I said, I don't think your parameters are incorrect. It's more of a control issue & in answer to your original question, I wouldn't change to rads, change the controls.
I have UFH since 2003 & certainly wouldn't change. Much more comfortable living with UFH over rads, but you've probably realised that with your own.

Since you have solar, your oil consumption for HW is probably in the region of €450 - €500 so your UFH costs is approx €2,000 - €2,050. Very easy to reduce that so long term, anything you spend will be recouped very quickly.

oikster

Shane you asked for return temps for this system. You did not receive an answer. You originally stated that it would not be easy to diagnose the problem without all the info. You now deem this install to be perfect without all info and are advising OP to spend more money. You do not know the depth of concrete on the ground floor. You do not know the length of the loops in this system. You do not know how long it takes the system to heat up. You tell the OP that the system shouldn't run constantly and then recommend a system that has the system constantly calling for heat.What size of buffer do you recommend. Why are you recommending a buffer. And finally is concrete really better than liquid screed .

shane0007

oikster wrote: »

Shane you asked for return temps for this system. You did not receive an answer. You originally stated that it would not be easy to diagnose the problem without all the info. You now deem this install to be perfect without all info and are advising OP to spend more money. You do not know the depth of concrete on the ground floor. You do not know the length of the loops in this system. You do not know how long it takes the system to heat up. You tell the OP that the system shouldn't run constantly and then recommend a system that has the system constantly calling for heat.What size of buffer do you recommend. Why are you recommending a buffer. And finally is concrete really better than liquid screed .

That's a lot in one mouthful :-)
I did indeed ask those. By experience, nearly all systems are designed on a CAD system specifically with the heat source in mind & laid in that manner. When I see certain important parameters adhered to & the trouble & expense of Easiscreed used, I would be surprised if other parts of the installation were scrimped on.
The OP never stated a poor heat from the system, it was more of a running cost issue, to the point where they are considered abandoning the UFH & going with rads. That ain't going to be cheap.
Also by experience, where I find expensive running costs on UFH being heated by an oil boiler is generally down to poor controls.
I did ask for flow & return temps & OP said flow was 40C which is fine. Return temp would be handy to know & if coming in at circa 29-30C, then manifold overall is balanced which would imply the individual flow rated won't be that far out.
Ground floor concrete depth will most likely be 75mm.
I did not recommend installing a system that is constantly calling for heat. It will set back to a lower desired room temp & as the OP stated the house is very insulated, the temp drop in the house over a few hours should not drop dramatically.
Buffer tank size, I did not go into great detail as not many people have the room for them, but generally I personally, for oil, would never go above 500 litres. This will give for an average house demand of circa 50w per sqm approx 90 - 120 minutes of heat for an input of approx 45 minutes (that's from cold).
The buffer tank is our source of modulation. If we can ever get a modulating oil boiler, we won't need a buffer with an oil boiler. Until then, a buffer makes for very low wastage of our boiler runtime & no over-firing, for example, OP's existing demand for UFH is 232sqm x 50 watts = 11.6kw. System losses will be minimal as they are lost to the floor so it's only pipework to manifolds. C26 will most likely be firing at factory setting of 23kw. Double the required, so will be short cycling like mad. Answer: a buffer! Heat the buffer, draw the low demand as required. Lowest allowable temp of buffer will be 40C.

Take the HW demand directly from the boiler when required, perhaps 30 mins in the morning & 30 mins in the evening. Use the diverted valve for this.

oikster

Seeing as you started your post with an insult I will keep my reply brief. I have read your post and words like "if", "circa" and "likely" tell me all I need to know.

Wearb

Interesting thread.

I would have preferred it if my (this one) post had gotten into post #38 position.

shane0007

oikster wrote: »

Seeing as you started your post with an insult I will keep my reply brief. I have read your post and words like "if", "circa" and "likely" tell me all I need to know.

If you took that as an insult, then you should try & work out what smiley faces are used for. No need for crap.
If the OP does not require or want my advice then I won't post again or perhaps you are just looking for an argument.

Wearb

oikster wrote: »

Seeing as you started your post with an insult I will keep my reply brief. I have read your post and words like "if", "circa" and "likely" tell me all I need to know.

AH HERE! oikster

pat35

shane0007 wrote: »

That won't be a problem. Easiscreed is more suitable for upstairs anyhow as bedrooms require less reaction time. Downstairs is better with more thermal mass.

As I said, I don't think your parameters are incorrect. It's more of a control issue & in answer to your original question, I wouldn't change to rads, change the controls.
I have UFH since 2003 & certainly wouldn't change. Much more comfortable living with UFH over rads, but you've probably realised that with your own.

Since you have solar, your oil consumption for HW is probably in the region of €450 - €500 so your UFH costs is approx €2,000 - €2,050. Very easy to reduce that so long term, anything you spend will be recouped very quickly.

Shane, The oil the boiler is heating the HW cylinder 24/7 to say 60 degrees is there any savings by having the solar at all.If even having time clock/controls for HW could there be a saving of upto 300 euro+ pa?

Ah Here

shane0007 wrote: »

That's a lot in one mouthful :-)
I did indeed ask those. By experience, nearly all systems are designed on a CAD system specifically with the heat source in mind & laid in that manner. When I see certain important parameters adhered to & the trouble & expense of Easiscreed used, I would be surprised if other parts of the installation were scrimped on.
The OP never stated a poor heat from the system, it was more of a running cost issue, to the point where they are considered abandoning the UFH & going with rads. That ain't going to be cheap.
Also by experience, where I find expensive running costs on UFH being heated by an oil boiler is generally down to poor controls.
I did ask for flow & return temps & OP said flow was 40C which is fine. Return temp would be handy to know & if coming in at circa 29-30C, then manifold overall is balanced which would imply the individual flow rated won't be that far out.
Ground floor concrete depth will most likely be 75mm.
I did not recommend installing a system that is constantly calling for heat. It will set back to a lower desired room temp & as the OP stated the house is very insulated, the temp drop in the house over a few hours should not drop dramatically.
Buffer tank size, I did not go into great detail as not many people have the room for them, but generally I personally, for oil, would never go above 500 litres. This will give for an average house demand of circa 50w per sqm approx 90 - 120 minutes of heat for an input of approx 45 minutes (that's from cold).
The buffer tank is our source of modulation. If we can ever get a modulating oil boiler, we won't need a buffer with an oil boiler. Until then, a buffer makes for very low wastage of our boiler runtime & no over-firing, for example, OP's existing demand for UFH is 232sqm x 50 watts = 11.6kw. System losses will be minimal as they are lost to the floor so it's only pipework to manifolds. C26 will most likely be firing at factory setting of 23kw. Double the required, so will be short cycling like mad. Answer: a buffer! Heat the buffer, draw the low demand as required. Lowest allowable temp of buffer will be 40C.

Take the HW demand directly from the boiler when required, perhaps 30 mins in the morning & 30 mins in the evening. Use the diverted valve for this.

I appreciate all the info Shane, fair play.

If i do the following:

1. Timer on the hw.
2. Replace the stats/controls

Any idea of cost? Considearing i have 8 stats to replace

shane0007

pat35 wrote: »

Shane, The oil the boiler is heating the HW cylinder 24/7 to say 60 degrees is there any savings by having the solar at all.If even having time clock/controls for HW could there be a saving of upto 300 euro+ pa?

Not in the winter but I would doubt very much the OP has the UFH on during the summer & is most likely getting close to their requirements on decent summer days by solar & just topping up when required.

shane0007

Ah Here wrote: »

I appreciate all the info Shane, fair play.

If i do the following:

1. Timer on the hw.
2. Replace the stats/controls

Any idea of cost? Considearing i have 8 stats to replace

I'm not saying that. I am only giving you pointers trying to guide you in the right direction. A survey of the system could well reveal other issues or confirm my suggestions.
Cost wise would depend on whether your existing wiring to the stats can be re-used. Generally it is Cat5e screened but can be mains also. Heatmiser do a few to suit the various requirements. A UH1 control centre would be also required.
I would also include upstairs as your system was designed to heat both & should easily heat both economically if the changes I suggested solved the problem.
Upstairs with easiscreed would only need to on for limited periods but definitely worth while.

Ah Here

It looks like mains wiring. Ill see if heatmiser have a rep who could have a look

shane0007

Ah Here wrote: »

It looks like mains wiring. Ill see if heatmiser have a rep who could have a look

They also do mains units but it will depend on how many cores you have available. If you are struggling on the number of cores, they do a battery one that will just require the switching circuit cores.

Their technical department is in the UK, but you can call them on 01-4852893. This will divert to UK with them paying the divert international rate.

Before you go down the route of replacing units, you really need to get a survey by somebody who knows what they are looking at, preferably from somebody that is not sales orientated.

Irish Steve

Can I throw in a couple of thoughts.

The only mention of insulation was in the first post, "well insulated", which could mean anything, given the way things are with insulators and what was regarded as well insulated 10 years ago means very little now with the way the standards have been changed.

Are the walls cavity or solid, if they are cavity, are the cavities insulated, or filled, or has anything been done in that area.?

What depth of insulation is in place in the ceilings? Is the upper floor across all the lower floors, or are we talking dormer here, so some ceiling area above the ground floor is not covered by upper floor.?

Has any checking been done on how airtight the house is, to try to determine how much heat is being blown out by draughts?

How well insulated is the hot water tank, given it's being heated 24/7. ?

Reason I ask is that we're in a 3000 Sq Ft Dormer bungalow 2000 lower, 1000 upper floors that was built in the early 90's, and it was horrendously expensive to heat (traditional radiators on a 120,000 Bthu Sime oil boiler. ) What has made a significant difference is that the cavities were filled last summer, and we've noticed a difference with just that done.

There's still a job to do to reduce the airflow up one of the chimneys, which is not as simple as sticking a balloon in it, as it's above a gas fire, which was put in to cover emergencies ( I will never be single fuel again, having been caught by rota power cuts in the UK in the 80's, even the oil system needs electricity, although I do now have a generator for that, it came to support a computer after we'd moved in), and I need to do a major job to reduce the wind effect through the roof, the other issue being no insulation under the dormer floor, so a huge potential heat loss there that was only partly blocked with polystyrene blocks in the joists to block the airflow, once I'd found the problem the first winter here.

I guess what I'm getting at is that if the heating is costing €2500 to run, a significant portion of the heat is going somewhere that it shouldn't be going, and changing to radiators won't necessarily solve the problems of heat loss, they will just change how the heat is delivered into the rooms that are losing it.

Shane's comments about boiler servicing are relevant, I've just had mine done recently, having not had it checked for a while, and that has also helped.

UFH is best suited to a house that's being actively used for long periods of the day, in that it's providing a reservoir of heat in the floor that's being held at a reasonably static temperature, and changing the temperature of the floor slab doesn't happen quickly, whereas radiators will pull a room air temperature up quickly, though getting the fabric of the building up to temperature still takes time. If the air is warm, the occupants feel warm, even if the fabric of the building is still coming up to temperature, so if there are periods of non occupancy, then UFH may well not be the most economic solution to heating the house.

Heating the hot water 24/7 is probably costing you money, unless there's a houseful of people taking showers at all sorts of strange times, most of the time, we need 2 periods of under 1 hour per day to ensure sufficient hot water for pretty much most situations, unless we have visitors, and even then, a 1 hour boost is plenty to cover what's needed.

Hopefully some food for thought.

Ah Here

Thanks for your input Steve,

I built the house myself with direct labour so I was sure the house was well insulated - 100mm under the subfloor, 50mm kinspan in the walls, insulated slab and regular insulating in the roof of upstairs, insulation in the ceilings and under the upstairs floor, with triple glazed windows throughout. My windows were put in by munster joinery and the two bathroom windows are a disaster, but I'll be getting them fixed soon.

I'm tending to agree about the hot water. We use it for baths/showers in the evening and for the washup, so it is really used only from say 5-9pm. the solar panel should heat it sufficiently during the day for all other needs. Some people say that it is more economical to heat it 24/7 instead of heating it up for a few hours and letting it cool again, but I have my doubts (although i am no expert) that it is very economical to be heating the water in the middle of the night for no reason.

Does the heating of the water for the HW affect the heating of the water for the UFH (excuse my ignorance!).

MicktheMan

Ah Here wrote: »

Thanks for your input Steve,

I built the house myself with direct labour so I was sure the house was well insulated - 100mm under the subfloor, 50mm kinspan in the walls, insulated slab and regular insulating in the roof of upstairs, insulation in the ceilings and under the upstairs floor, with triple glazed windows throughout. My windows were put in by munster joinery and the two bathroom windows are a disaster, but I'll be getting them fixed soon.

I have to agree with Irish Steve.
OP, in your post I've quoted above, there is no mention of air tightness measures. Now, while insulation is important, air tightness is just, if not more, as important as insulation. Especially in our mild but windy climate.

From experience of testing houses for heat loss, dormers are the worst (by far) for air leakage issues.

Perhaps you should consider having the house tested for heat loss mechanisms first because if, for example, the house is leaking like a sieve, then, no amount of tinkering of the heating system will be of much help.

Ah Here

MicktheMan wrote: »

I have to agree with Irish Steve.
OP, in your post I've quoted above, there is no mention of air tightness measures. Now, while insulation is important, air tightness is just, if not more, as important as insulation. Especially in our mild but windy climate.

From experience of testing houses for heat loss, dormers are the worst (by far) for air leakage issues.

Perhaps you should consider having the house tested for heat loss mechanisms first because if, for example, the house is leaking like a sieve, then, no amount of tinkering of the heating system will be of much help.

Thanks Mick,

I know the bathrooms are leaking heat as the windows are a disaster, so I will rectify that. I have one of the chimneys well stuff and don't ever use it, and the other chimney has a stove which is also stuffed. I also have big windows along one side of the house. Otherwise I'm happy that it is not leaking too much heat.

MicktheMan

Ah Here wrote: »

Thanks Mick,

I know the bathrooms are leaking heat as the windows are a disaster, so I will rectify that. I have one of the chimneys well stuff and don't ever use it, and the other chimney has a stove which is also stuffed. I also have big windows along one side of the house. Otherwise I'm happy that it is not leaking too much heat.

Again from experience, windows tend to be fine. It's everything else that can be an issue. But, if you are happy that you don't have air leakage issues and draughts, then I'll bow out.

Irish Steve

Ah Here wrote: »

Thanks for your input Steve,

I built the house myself with direct labour so I was sure the house was well insulated - 100mm under the subfloor, 50mm kinspan in the walls, insulated slab and regular insulating in the roof of upstairs, insulation in the ceilings and under the upstairs floor, with triple glazed windows throughout. My windows were put in by munster joinery and the two bathroom windows are a disaster, but I'll be getting them fixed soon.

I'm tending to agree about the hot water. We use it for baths/showers in the evening and for the washup, so it is really used only from say 5-9pm. the solar panel should heat it sufficiently during the day for all other needs. Some people say that it is more economical to heat it 24/7 instead of heating it up for a few hours and letting it cool again, but I have my doubts (although i am no expert) that it is very economical to be heating the water in the middle of the night for no reason.

Does the heating of the water for the HW affect the heating of the water for the UFH (excuse my ignorance!).

OK, if the hot water is running full time, then the boiler content has to be kept hot, and the water that's circulating is also being heated, which could mean the boiler is short cycling if the hot water is already pretty hot, which is not good, it's better to let things cool, and then give the thing some real work to do, if for no other reason than the heat loss from boiler, pipes etc is greater the higher the differential is between the pipes and the surroundings. So, if the pipes are cool, then are not going to lose heat in the way they do when they are hot.

The Hot water needs to be times and zoned on a motorised valve system, so that if the solar is doing the job it's there for, the boiler is out of the loop completely, and not even cycling. I don't have solar, but my next door neighbour does, family of 4, and they don't need any additional heat input into their hot water system from March to October, the solar gives them all they need. The Solar should be a lot cheaper than using oil for hot water, especially in the summer, and even in the winter, it will make a useful contribution, I'd be looking at something like a 1 hour boost in the morning from the oil, and then a 1 or 2 hour boost in the evening, with a thermostat on the tank to stop the oil if the hot water is hot enough, that will only then call for heat from the boiler if it's really needed.

I don't have enough experience of UFH to be able to suggest a temperature profile for running it, but given the mass of the floor, the changes need to be relatively small, but my gut instinct is that the temperature could be lowered by several degrees at least an hour before people are going to be heading for sleep, and then raised an hour or so before rising time, but it is going to be a case of experimenting with it, given that each floor will have different response times. That for me is the downside of UFH, the fabric of the building is the heat source, so it has to heat the air to make the occupants comfortable, radiators heat the air that then heats the fabric. and most of the time, the differential temperature is much higher with radiators, so the heat transfer is a lot quicker.

I'm thinking aloud here, and could be laying myself open to some criticism or correction on this, my gut instinct (again) is suggesting to me that UFH is only part of the solution, and to get best economy, the UFH needs to be used to provide a background level of constant heat, but below total comfort levels, (because of the long response times) with either radiators or hot air circulation then being used to provide the "comfort boost" adjustments that is needed to make areas more comfortable during peak usage. The issue there is going to be that ( as I understand it) UFH is normally operating at a much lower temperature than a radiator system, so running the two concepts off the one heat source is going to be problematic, unless some form of heat buffer is used to run the UFH, along the lines of a hot water cylinder, so the boiler is not driving the UFH directly. That may be just so much horse feathers, and I'm sure that some of the more experienced people here will either shoot me down, or provide some more suitable comments to either expand this or kill the idea completely.

If nothing else, it's got my brain working along different lines to the way if often does, I just hope it's not going down the wrong route, given the importance of getting this sort of thing right, changing it after the install is not easy.

Wearb

Have you ruled out leaks? How far from your dwelling is the oil boiler? You are loosing heat somewhere. Even with your set-up; a well insulated DHW cylinder should not cause the sort of consumption that you are experiencing, especially with your insulation specs. As already suggested, an air tightness test would not go amiss.

Ah Here

Wearb wrote: »

Have you ruled out leaks? How far from your dwelling is the oil boiler? You are loosing heat somewhere. Even with your set-up; a well insulated DHW cylinder should not cause the sort of consumption that you are experiencing, especially with your insulation specs. As already suggested, an air tightness test would not go amiss.

Thanks for your input. The boiler is in the shed, some 6 feet from the house. I don't see any leaks and I would do ans the pipe is underneath cobble and would seep upwards.

I'll have to see what is the most economical way to fix this issue. An air tightness test would cost money as would upgraded controls. I don't have the money to throw at it.

timmy4u2

Ah Here wrote: »

Thanks for your input. The boiler is in the shed, some 6 feet from the house. I don't see any leaks and I would do ans the pipe is underneath cobble and would seep upwards.

I'll have to see what is the most economical way to fix this issue. An air tightness test would cost money as would upgraded controls. I don't have the money to throw at it.

As I said before get some Solo rads. You will automatically have control in each room and you will be amazed at the heat and the fuel savings, and they will not cost you an arm and a leg.

Ah Here

timmy4u2 wrote: »

As I said before get some Solo rads. You will automatically have control in each room and you will be amazed at the heat and the fuel savings, and they will not cost you an arm and a leg.

thanks timmy, but again I don't have the money to spend that much.

timmy4u2

Ah Here wrote: »

thanks timmy, but again I don't have the money to spend that much.

Underfloor heating in a home, I do not subscribe to it. Everybody I know with it, and that would be only ten or twelve people, have nothing good to say about it.
The Solos are about €380 each new. I bought four of them, slightly used, for less than €400.
I fitted them myself. You have a stove in one of the fireplaces. Go to solid fuel and you will recoup what you have spent in one year.
I have excellent heating for about 12 hrs every day and my total fuel costs will be less than €1000 for the winter.
I have also saved 28.8% on my electricity since I installed the Solos by not needing to use electric heaters to boost the heat.

Wearb

Ah Here wrote: »

Thanks for your input. The boiler is in the shed, some 6 feet from the house. I don't see any leaks and I would do ans the pipe is underneath cobble and would seep upwards.

I'll have to see what is the most economical way to fix this issue. An air tightness test would cost money as would upgraded controls. I don't have the money to throw at it.

Checking for a leak isnt difficult. You might be able to have a look over your house yourself during a windy day to see if you have draughts.
Are your pipes from the shed to the house well insulated and in waterproof ducting? If you put your hand on the outside casing of the boiler when its been running for a couple of hours, does it feel warm? Maybe post a photo of your boiler here. Insist on a combustion performance printout. It could be running way off peak performance.

Ah Here

Wearb wrote: »

Checking for a leak isnt difficult. You might be able to have a look over your house yourself during a windy day to see if you have draughts.
Are your pipes from the shed to the house well insulated and in waterproof ducting? If you put your hand on the outside casing of the boiler when its been running for a couple of hours, does it feel warm? Maybe post a photo of your boiler here. Insist on a combustion performance printout. It could be running way off peak performance.

I'll have a look. I wouldn't be surprised if it wasn't insulated as my plumber was, let's just say, not that thorough.

Wearb

Ah Here wrote: »

I'll have a look. I wouldn't be surprised if it wasn't insulated as my plumber was, let's just say, not that thorough.

Those sort of little things make a difference if there are many of them.
Often when servicing during a frosty time, I can see the thawed line of frost where the underground pipes have been heating the ground (or the cat sitting on that area when there isn't any frost). Also wet insulation is almost as bad as none. I have lost work (plumber referrals) by telling new-build owners to insist on proper insulating and watertight ducting when placing the boiler away from the house. You could be loosing the equivelant of a 3 or 4 Kw into the ground if there are long runs of pipe. That could be 15 or 20% of your boiler output.
Read over the posts on this thread again and pick some of the cheapest fixes first. Your problem is probably a combination of lots of small issues.