Underfloor Heating & Solar Panel

Outkast_IRE

CotBC wrote: »

Since I was involved in this thread over a year ago, and got some good information from Mike, I figured it might be of interest to provide an update on how my own system is performing.

The background is that that we moved into our new build at the start of December 2010, so just over the 1 year mark at this point. House is 306m2 (3,300 sq ft), timber frame, UFH on ground and first floors, 250mm wall insulation (0.18 nominal u-value), 150mm floor insulation (0.15 nominal u-value), 400mm attic insulation (600mm in one annex (I had some extra rolls!), triple glazed windows (0.9 average u-value). Heating system comprising of a 750l buffer tank with 5 coils (2 x solar, 2 x DHW (1 preheat and 1 final heat) + 1 for back boiler), 2 solar panels (6m2 aperature area), 15kW insert fire with back boiler (2/3 to boiler, 1/3 to room), MHRV and an oil boiler.
Heatmiser stats in all rooms with a central LCD control panel (so useful!), a Horstman timer controller for the recirculation loop and the towel rails, and an M type controller for the heat inputs to the buffer tank. Tank is located in the garage with about a 10m run back to the house.
I don't have the air tightness test repeated yet, nor the BER rating so can't give figures for those.
House has a significant amount of North and East facing glass (the price I pay for maximising the sea views!), has a 5 person household and is heated for 24/7 occupancy.

Heating systems basically operate in line with what Mike has advocated many times on this thread.

Buffer tank inputs are all controlled by the M controller, with the oil boiler only being called on when the tank temperature drops below a preset level and then only when time lockouts are not in effect. The reason for including time lockouts was because I found during the summer that there were often cases when the tank temp would drop just below the trigger temp in the morning (after showers, etc.), and thus switch on an oil burn, where, if it had waited for an hour or so, the solar panels would be providing the necessary heat input. There are many ways to facilitate such an interlock, but the M controller has the timer function available as part of each function block, so it was an easy and effective option for me.
On a related topic, I did invest in a VBus to LAN adapter, so that I can log the system performance on a computer. Once I had put in the time to get my excel file automated, it only takes a couple of minutes to copy and paste the daily text file into excel and see the system performance for the day. By allowing me to monitor the system performance over extended periods of time and adjusting settings accordingly, that piece of kit has easily paid for itself in the first year in terms of oil saved! The dedicated datalogger is the other option there, but I was trying to keep the costs down at that stage. The other advantage of the LAN adapter is that I have the program backed up on the computer and I can make any changes from there which is certainly easier than trying to navigate through the menus on the controller. It also makes it easy to have separate programs, so it looks like I will have a Summer and a Winter program (mainly just the timer lockout previously referred to which is not in place for the winter months, and a slightly different trigger temp for the boiler).
Note that it is better to set a static IP address on the router for the LAN adapter just to simplify things.

So, getting back to how things have been going!
Bottom line is that I filled the 1,100l oil tank in November 2010 before we moved in, and it lasted until November 2011 when I had to put in 919 litres to fill it again. That was despite the fact that we burned through over a third of the tank in the first 6 weeks due to a combination of the house drying out, UFH settings not optimised, very cold weather and not least because the electrician had wired it up wrong so that it was short cycling constantly. After I re-wired the boiler control by inserting an aux. relay which is switched by the M controller, it only operates as required by the temperature in the upper section of the buffer tank. The only reason for using an external relay for the oil boiler was because the potential max load conditions of everything being switched were getting uncomfortably close to the max rating for the controller, so better safe than sorry.
A side benefit of having the M controller switching it is that I can see from the data log how long and how often the oil boiler runs each day.
This winter the oil consumption maxed at just under 50l per week during the cold spell in December, which was higher than I would have expected, but it is keeping house temperatures at levels for 24/7 occupancy, and in fact some of the preset temperatures were higher than they needed to be and have been dialled back since then. At the moment it's averaging around 30l per week consumption, and that's with very dull weather so the solar input is negligible most of the time.

It's important to note that we do light the fire most evenings, and that does give a nice amount of warm air into the building. Even with only the theoretical 5kW being transferred to the room (5.5m x 4.5m), it is a very warm room after a 4 or 5 hour burn ("cozy" for the wife, too hot for me!). The HRV does it's bit to distribute the heat by pushing it out the door of the room, but unless I maxed the fan speed, there is no way there would be sufficient air transfer to handle the heat load. For reference, increasing the fan speed on the HRV does make it audible upstairs when anywhere close to the ceiling inlets/outlets (it's located in the attic). The temperature in the room will drop a couple of degrees over night, but it will still be the warmest room in the house in the morning (door left open over-night). We bought 10 cubic meters of firewood last summer and it looks like we will go through most of it. That is more than is strictly necessary, but we like the "comfort factor" of having the fire lighting, and the fact that it is a renewable fuel makes it worth the effort for us. I cannot stress enough how important it is to get dry seasoned wood for burning. After we moved in we got a load locally which was supposed to be seasoned, but the reality was that it was far too green and would have needed another year to dry out properly. The result is that it did not burn hot enough in the stove and caused a lot of tar build up under the boiler with the resulting drop in efficiency and the soot builds up on the glass door at a frustratingly rapid rate. Last summer we bought timber that was 2 years cut, but we had to pay a premium for it, and it is increasingly difficult to get. These were large blocks (400mm length), which have the added benefit that 2 or 3 of those keep the fire going for a good long burn without having to keep checking on it. If you are seriously looking at the stove option, you will need to factor in the construction of a timber shelter large enough to allow buying the timber a year in advance so that it's properly seasoned before burning ... aim for <20% moisture. On that subject, I did get a moisture meter for approx. EUR20 after our initial experience, which showed that the original timber had moisture levels in the high thirties and some of it well over 40%.

The back boiler input to the buffer tank is a bit of a mixed bag! One negative with my arrangement where we have the buffer tank in the garage, is that the pipes from the back boiler have quite a long run to the tank. That would not have been much of an issue except for the fact that the manufacturers specified that ONLY copper piping could be used, so despite lagging those pipes as much as we could, there is still significant heat loss on the transfer to the tank. Originally, the system was setup having a standard pipe stat by the boiler which switched on the circulation pump when the back boiler water temp hit 60C and switched off when it dropped below 40C. After monitoring the way that was performing for a while (by monitoring the tank temperatures), I changed out the pipe stat and replaced it with a PT1000 sensor and again used the M controller to take over these functions. Program was setup to use a DeltaT trigger mechanism instead of fixed temperatures, with the circulation pump being switched on when the back boiler temperature is 15C higher than the middle of the buffer tank and off again when the temp difference drops to 5C (coil for back boiler is in the bottom section of the buffer tank). This allows it to automatically compensate for the initial high heat losses until the pipes heat up, and then keep the system running at good efficiency levels. Over the course of an evening, it will generally raise the temp at the very bottom of the tank by about 5C and the middle of the tank by 10C to 15C (that's heating approx 500l of water).

Finally, on the sizing of the buffer tank. This is one I don't have any good answer on. As I mentioned we went with a 750l tank based on the recommendation of the supplier. I tend to think of it as a 500l tank on the bottom and 250l on top ... there is a baffle in the middle to help with the stratification. I did put in 4 x PT1000 sensors for monitoring the tank performance and I can say that the stratification or layering of the temperatures does work very well. A typical Winter situation would be to have the bottom of the tank at 20C, the next sensor at 45C (top of the bottom section), the next sensor at 50C (bottom of the top section) and the top of the tank at 60C ... hope that makes sense! You will see some mixing at the mid levels during an oil burn, but it quickly settles down again.
One thing I did find last summer is that 2 or more consecutive long sunny days causes problems as the tank reaches max capacity and we do not use anything near enough hot water to take sufficient heat from the tank to compensate for the solar input. On the plus side, the 6m2 solar tubes I got can very effectively heat 750l of water when the sun is shining ... we just can't use that much and have no further storage. While I am on the solar subject, I will say that I found trying to select the solar tubes a very frustrating experience ... it is challenging to say the least to try to cut through the sales blurb and to get the relevant data from all the suppliers to make a realistic data driven comparison.
I am going to have to include a heat dump mechanism before this summer, which unfortunately will probably be a water flush. I did some trials last year by turning on the heated towel rails, but they did not take anything near enough heat out of the tank. The other downside with using the towel rails was that the last thing I wanted to do was add any more heat to the house, as we struggled last summer to keep the temperatures low enough in the house ... that on a very dull and relatively cold summer. Don't underestimate the potential for solar loading in rooms if you have large south facing glazed areas (we did not have curtains hanging on the relevant windows at the time), and be sure to disable the heat recovery function on the MHRV during the summer months!
So for the tank size, you will get any number of opinions on this but for me it's a trade off between having a big enough buffer during the summer to take the solar input vs. not having a huge (expensive) body of water to have to heat during the winter months. Therein lies the challenge...

OK- that was longer than I had planned - apologies if I went off on too many tangents.
Anyway, for those of you starting out in all of this - Good Luck!
I'm not sure if any of the above actually helps or just confuses the situation more, but it's my 2 cents worth based on my own experience.

BR,
Tim

Very Intersting read , you have built basically the same setup that i have been recomending to people doing new builds for years. Unfortuntatly none of them can see past the short term costs to the long term savings.

The length of run between your back boiler and buffer seems your only real problem area , and thats unavoidable really if you dot want the buffer in the house.

Its good to see the solar linked to the buffer working so well. Best of luck with it .

The only part i would need to wrap my head around on such a project is the controls for everything.

fclauson

So you want to know how to map all this stuff together

here is my first attempt - still working on it

kboc

Really impressive tim, well done.

Great to see people investing the time into researching different situations and having the foresight to see the benefit of this.

K

beyondpassive

Excellent Post. We def need more post occupancy evaluations.

I think Architects and designers need to realise that we're past the days of outside boiler rooms and hot presses . Stratified Thermal stores of 750 or 1000litres have eliminated the hotpress with its cylinder and because its best to have the boiler close to the store and within the thermal and airtight barrier, houses now will have a plant room. If a press is needed for heating it will have a towel rail and MHRV extract.

We also use the Thermal store as a 'renewable technology' under DEAP to contribute heat from the solar buffer (lower section) to the space heating. which also reduces the amount of solar we need to meet Part L. This is done through the underfloor circuits which have either 2 coils or plate exchangers in the tank and a mixer. We have additional underfloor loops or occasionally towel rails on a 'discretionary circuit' which heats toilets and en-suits and with underfloor is linked to a stat in the floor, where floor temperature is set. This means that the floor can be set to be toasty before your morning shower, this heat also helps the room dry out and this heat is easily recovered through the MHRV exchanger. The discretionary circuit is also used for summer overheat once the tank hits its 60 degrees on top and 40 below, when the wet rooms heat up to their set points the tank will vent hot water to a waste drain.

It's great to see that others are finding that this is the optimum system and just as I've just got my head around the hardware, it great to have the brains of Mike, Tim and FC give a masterclass on the software side. Thanks.

brophis

Nice feedback Tim. Quick question regarding the screed for ufh, I guess you went for the liquid type screed upstairs being timberframe and all but did you also go for the same downstairs or did you go for sand/cement type screed downstairs? If different, how do you find both?

fclauson

beyondpassive wrote: »

.....
We also use the Thermal store as a 'renewable technology' under DEAP to contribute heat from the solar buffer (lower section) to the space heating. which also reduces the amount of solar we need to meet Part L. .....

See http://www.seai.ie/Your_Building/BER..._Systems_.html for what BP is talking about

CotBC

brophis wrote: »

Nice feedback Tim. Quick question regarding the screed for ufh, I guess you went for the liquid type screed upstairs being timberframe and all but did you also go for the same downstairs or did you go for sand/cement type screed downstairs? If different, how do you find both?

Yes on the screed, 50mm liquid pour upstairs and 75mm sand/cement downstairs. The main difference I see is on the heating times for the slabs, where upstairs will heat noticeably faster. With that said, it's difficult to make a direct comparison since the rooms downstairs are generally not comparable to upstairs in terms of size, number of windows, etc.
In practice it's just a matter of seeing how each room is performing and adjusting the timers on the stats accordingly to call for heat when required.
e.g. Require 20C in a room from 6pm to 10pm, then set stat program to have the room at 20C from 5pm to 10pm. Assuming the room temp is <20C at 5pm, the heating loop gets activated and as soon as the room temp is reached, the actuator shuts off so you are not going to be wasting any hot water by leaving the 20C setting on the stat until 10pm.

The heavier slab requires more time to heat up, but also more time to cool back down and conversely for the thinner slab.

beyondpassive

beyondpassive wrote: »

Excellent Post. We def need more post occupancy evaluations.

I think Architects and designers need to realise that we're past the days of outside boiler rooms and hot presses . Stratified Thermal stores of 750 or 1000litres have eliminated the hotpress with its cylinder and because its best to have the boiler close to the store and within the thermal and airtight barrier, houses now will have a plant room. If a press is needed for heating it will have a towel rail and MHRV extract.

Would most people not have the boiler outside to avoid the smell, the noise but mostly for safety ? It would also need an air supply ??

fclauson

Deleted User wrote: »

Would most people not have the boiler outside to avoid the smell, the noise but mostly for safety ? It would also need an air supply ??

On the noise - depends - many new boilers are very quiet
On smell - agree - that is why I am going gas (oil is smellly)
On safety - not sure - 1000s already live inside
On air - there are ways of achieve this with balanced flues etc

Reasons for being inside
1 - no heat loss - all warmth ends up inside the thermal envelope
2 - no losses as its ducted across the garden (you will be amazed at the losses via this route)
3 - no cycling in the cold weather - systems outside need frost stats which make the system cycle if they get cold - which is a waste if they are not needed

sas

fclauson wrote: »

On smell - agree - that is why I am going gas (oil is smellly)

LPG or are you fortunate enough to be on the gas line?

fclauson

sas wrote: »

LPG or are you fortunate enough to be on the gas line?

SAS - changed from Oil to LPG - clean, does not smell, boiler modulates, can be inside, little or no servicing, quiet

but agree more expensive than oil per Kwh
http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/Domestic_Fuel_Costs_Comparison_October_2011_pdf.pdf

but I think the best choice (I hope )

Mike2006

Sorry - Can't do 'quotes' properly...

For my hot-return Loop, I ran a live from the light switch to the bathrom to a contactor on my main board. This contactor feeds the Hot-Return Pump.

So, when I turn on the light in the bathroom, it pulls in the contactor and this runs the hot-return pump. When I turn off the light, the pump stops.

I always turn on the light in the bathroom so this works for me.

Mike.




Quote:
Originally Posted by Mike2006
...You could have the hot return loop pump on a timer and have it pulling at certain times during the day when you 'know' you will need hot water (i.e. shower time, wash-up time after dinner) and then just wait for the loop all other times. I would not run the loop 24/7 if I were you.

Mike - I thought of putting a flow switch on the h/w loop so that when a tap is turned on the pump runs (say for 10 mins so it does not cycle on/off/on/off) so you get h/w faster than you would have had running the tap - but slower than if the pump was on permanently

I would then put a timer on the pump so its on as you suggest at "know" need times

Francis

Outkast_IRE

Deleted User wrote: »

Would most people not have the boiler outside to avoid the smell, the noise but mostly for safety ? It would also need an air supply ??

Oil inside is very safe as long as the proper safety valve on the oil line are fitted, unfortunatly some installers still insist on using ones which dont meet the regs .

Honestly if the oil line into my house had a proper shut off valve i would say its as safe as the gas.
But no matter how well built the oil burner i always seem to get a bit of a smell off them .

Another thing to be carefull of is people trying to site the tank up against an outside wall of the house , thats a big no no as far as the regs are concerened .

Also in terms of air supply , most of the new oil burners are available with balanced flues where the air for combustion is taken from outside.

Old Jim

The word buffer suggests that a second tank is required. Is this correct?
And what are the benefits of the larger tanks (750L/1000L)? Is it the ability to store more solar energy for longer?

fclauson

Old Jim

one of the challenges is energy storage - a thermal store allows you to hold considerable energy (about 50Kwh in 1000 litres dependant on temp) so for solar this could be captured during the day - and prehaps in the evening captured from your back boiler.

the store is about smoothing out the supply and demand graphs a little

beyondpassive

Old Jim wrote: »

The word buffer suggests that a second tank is required. Is this correct?
And what are the benefits of the larger tanks (750L/1000L)? Is it the ability to store more solar energy for longer?

You have a choice to use 1). a water cylinder and a solar buffer tank, 2) a preheat store and thermal store and 3) a combined store. I like option 3 because, the top of the top section is kept at 60 degrees for indirect hot water and the top of the bottom section at 40 degrees, which feeds the exchanger/coil for a low temp space heating system like underfloor or towel rails. This works wel with solar which at certain times in Autumn and Spring is about 36 degrees anyway.

Old Jim

beyondpassive wrote: »

You have a choice to use 1). a water cylinder and a solar buffer tank, 2) a preheat store and thermal store and 3) a combined store. I like option 3 because, the top of the top section is kept at 60 degrees for indirect hot water and the top of the bottom section at 40 degrees, which feeds the exchanger/coil for a low temp space heating system like underfloor or towel rails. This works wel with solar which at certain times in Autumn and Spring is about 36 degrees anyway.

Thanks for the explanation. When you say a combined store, is that a "tank inside a tank" or a stratification tank? Is a 1000L buffer tank a combined store?
I also like the idea of heating one large tank that can supply water at various temps where it is needed. Sorry for the prob basic questions!

Do-more

Old Jim wrote: »

"tank inside a tank" or a stratification tank

I'd also like to hear the considered opinion of Tank in tank Vs Stratified tank.

CotBC

Do-more wrote: »

I'd also like to hear the considered opinion of Tank in tank Vs Stratified tank.

I can't give any information on the tank in tank option as I opted for the single tank option so I have nothing to compare against. For the stratified tank, I think the best I can offer if to just give you some data from my own system as it is operating.
Since I have given an overview on a previous post, I will take the view that a picture is worth a thousand words, so the attached file contains a basic diagram of the overall system plus a few graphs showing the tank performance. I know the graphs look like a mess of lines at first glance, but hopefully I have put in enough information there to help make sense of them after a bit of study! I did also include a photo of the partially installed tank just to put things in perspective (brand name has been removed to protect the innocent!).

If anybody has some similar information for a tank in tank version, I would be interested to see it for comparison (not that I am going to be changing at this stage).

Regards,
Tim

fclauson

Firstly fabulous post - nothing like real field data

I am at this juncture now with the options

a) 1 tank stratified or
b) 2 tanks (a Hot water one and a buffer/heat bank) giving you a hot water tank which is not affected by your heat demand
There are arguments for both approaches

for the heat source then
HP or Gas (both ideal inside)
Oil (better if sited outside of main envelope)
again each have their benefits

Couple of questions CotBC
1 - do you know if the heatmiser has weather compensation - i.e. is there a probe outside and does the UFH pump vary in speed or does the temp being delivered to the floor vary on a heat curve (may be 25 degrees when its +10 out side but 35 when its -10)
2 - solid fuel back boiler - I assume the circ is vented with a small header tank somewhere in the loft or have you managed to do it as a closed circ
3 - what size boiler do you have (how many Kw)
4 - how many SqM of panels do you have - and what type/brand

One other comment - you burn at 9:30 in the morning - would you think of putting this off until later in the day hoping for some sun (unless of course you UFH or h/w is actually going to not have enough heat to function) - this predictive bit really interests me but its wholly dependent on occupant behaviour

CotBC

fclauson wrote: »

Couple of questions CotBC
1 - do you know if the heatmiser has weather compensaiton - i.e. is there a probe outside and does the UFH pump vary in speed or does the temp being delivered to the floor vary on a heat curve (may be 25 degress when its +10 out side but 35 when its -10)
2 - solid fuel back boiler - I assume the circ is vented with a small header tank somewhere in the loft or have you managed to do it as a closed circ
3 - what size boiler do you have (how many Kw)
4 - how many SqM of panels do you have - and what type/brand

OK, here goes;
1. No weather compensation on my setup, just a standard mixer valve on the line to deliver approx. 40C to the UFH. In reality if it is +10C outside, the UFH will probably not be used much ... goes back to the insulation, insulation, insulation argument!
2. It's actually a closed loop system since it has a dedicated coil in the tank. Because my tank is in the garage, I did not have the option of having a gravity loop, which is what I would have preferred because of the problem of no power = no water flow. The system does have a mechanical over-pressure valve and cooling loop valves to ensure safe operation in case of power cut.
3. Solid fuel back boiler is 15kW, with 10kW to water and balance to room.
Oil boiler is 35kW.
4. 6 sq. meters aperature area on the solar tubes. PM me for the brand or I'll get in trouble

CotBC

fclauson wrote: »

One other comment - you burn at 9:30 in the morning - would you think of putting this off until later in the day hoping for some sun (unless of course you UFH or h/w is actually going to not have enough heat to function) - this predictive bit really interests me but its wholly dependent on occupant behaviour

Sorry - missed this one!
Take a look back to my post on page 5 of this thread for my explanation on this ... during the summer, that is exactly what I do by locking out the oil until later in the day.

Jellybean13

quick question maybe you may know as you have underfloor heating. I have it downstairs. 4 minivalves outside and two stats (one in kitchen and one in hall)
bascally only half kitchen heats up and all hall apart from bathroom heats up.
Other half of kitchan and bathroom only heat up if I increase temperature in stat on wall subtantially (ie to a crazy temp like 25 or something)
Any ideas why all rooms are not uniformly heating.
oh and usually only 2 of mini valves on so its consistent in that 1/2 kitchen and bathroom are clearly not calling to be on eventhough they are all on same time clock.
Any advice would be greatly appreciated

fclauson

simple check the wiring and check mini valves

BEFORE YOU START - IF YOU ARE NOT FAMILIER WITH DOING THIS GET AN ELECTRICIAN - ELECTRICTY CAN KILL :mad:

work logically through each setting checking if the minivalve is being asked to open - if yes - but valve does not open then check minivalve (swap them over etc). if no then check wiring "logically" to ensure its set up as you expect

Can I suggest you draw a diagram first - and then label and colour code each cable as its tested otherwise you will duplicate or miss out on some testing

CotBC

Ditto on what fclauson said - there really is no quick way around it.
Just get one stat at a time to call for heat, and check that the relevant actuator / mini-valve is being activated. You should have gotten a loop diagram at the time of installation, so it's important to check that and mark it up with the relevant stat and valve info.
For reference, I did actually have to refurbish one of my manifolds after only one year. Thankfully, the supplier stepped up to the mark without any argument, as they could not believe that the valves has failed so quickly ... it seemed like they did not like being inactive for 9 months. Anyway when we went looking at it, we found 2 defective actuators (one had been cross threaded so the plastic plunger had cracked), 3 defective valves and one wiring error where an incorrect loop was being switched by a stat.
It was just a case of working through them methodically to verify the correct operation, and figure out root cause in each case.

BryanF

Jellybean13 wrote: »

quick question maybe you may know as you have underfloor heating. I have it downstairs. 4 minivalves outside and two stats (one in kitchen and one in hall)
bascally only half kitchen heats up and all hall apart from bathroom heats up.
Other half of kitchan and bathroom only heat up if I increase temperature in stat on wall subtantially (ie to a crazy temp like 25 or something)
Any ideas why all rooms are not uniformly heating.
oh and usually only 2 of mini valves on so its consistent in that 1/2 kitchen and bathroom are clearly not calling to be on eventhough they are all on same time clock.
Any advice would be greatly appreciated

any chance that there is not adequate insulation or there are thermal bridges in these rooms?

kboc

Jellybean13 wrote: »

quick question maybe you may know as you have underfloor heating. I have it downstairs. 4 minivalves outside and two stats (one in kitchen and one in hall)
bascally only half kitchen heats up and all hall apart from bathroom heats up.
Other half of kitchan and bathroom only heat up if I increase temperature in stat on wall subtantially (ie to a crazy temp like 25 or something)
Any ideas why all rooms are not uniformly heating.
oh and usually only 2 of mini valves on so its consistent in that 1/2 kitchen and bathroom are clearly not calling to be on eventhough they are all on same time clock.
Any advice would be greatly appreciated

i had this problem. it turned out, one of the plumbers men turned the screw on the manifold down fully, closing off that loop of pipe on the manifold. literally 10 secs fixed it

Toys Out Of The Pram

Ok so I'm very interested in the system have installed UFH in my sisters and am one of the electrcians who have read into everything and know what I'm after and how to do it. 2 questions

1. is there any particular issue with having the boiler in the garage and everything else in the house. will be having pipe in pipe across from plant room to garage the with insulation all filled up nicely dont ask me u values of it as i'm not that technical (Ive aloud for plant space inside the house but the boiler in there maybe a stretch too far)

2. Is there any requirement for the need of HRV? as from experience of the sisters house the boiler is only working the UFH for 6 months and off the rest of the time and good insulation does the job for the next 6 months.

House is 2,400 and will have UFH upstairs and down with hollowcore and alot of insulation and a certian amount of joint taping etc havent fully looked in to that yet

Cheers Toys

Do-more

@Toys It's better to have the boiler within the thermal envelope of the house as any heat losses from the boiler i.e. heating the air rather than the water, will still end up contributing to heating the house rather than going completely to waste in the garage.

Insulation is only one part of the equation, air tightness is the other equally important factor.

I know from practical experience that it is easier to keep my present house warm when it is -10C outside and no wind than it is in windy weather at +2C. The place is well insulated but leaks like a sieve, so in windy weather the heat is literally blown out of the house.

You really should pay close attention to air tightness measures and then have some form of controlled ventilation preferably with heat recovery. It will have a very significant effect on the heat losses from the house.

The other significant factor you should be looking at is to eliminate any cold bridges from the building.

fclauson

Toys Out Of The Pram wrote: »

Ok so I'm very interested in the system have installed UFH in my sisters and am one of the electrcians who have read into everything and know what I'm after and how to do it. 2 questions

1. is there any particular issue with having the boiler in the garage and everything else in the house. will be having pipe in pipe across from plant room to garage the with insulation all filled up nicely dont ask me u values of it as i'm not that technical (Ive aloud for plant space inside the house but the boiler in there maybe a stretch too far)

there will be some loss - but the insulated pipes are good these days.
Be carful with your system design oil & UFH do not go well together unless you have some form of buffer in the way - reason - oil boilers produce at 60 or 70 or 80 degress and UFH requires 25 or 30 or 35 - look at various posts around mine and BeyondPassive for system designs

2. Is there any requirement for the need of HRV? as from experience of the sisters house the boiler is only working the UFH for 6 months and off the rest of the time and good insulation does the job for the next 6 months.

Cheers Toys

That depends - if you get below 3 ACH then you will need MHRV - again see other posts - underventalaiton can cause majour problems (mould and mushrooms :mad:) - Read Part F on ventalaiton (specifically the table on rates required acrosss a house)