undetfloor upstairs in dormer

HoofRocks

Have recently been geeting quotes for air to water and geothermal heat pumps for our new build 1650 sq ft dormer bungalow.(1650 sq ft down stairs)

we had originally thought of putting underfloor downstairs and radiators upstairs however after much research, on this forum, and dealing with suppliers we understand that it would not be a good option.

We will have a high level of insulation and mhrv, a specialist company for air tightness and strong focus on cold bridging.

My question is, is there a need for underfloor upstairs in a dormer as the main living space is downstairs including master bedroom, and has anyone any experience of not putting it in and if so what is the temperature like

gooseygander

HoofRocks wrote: »

Have recently been geeting quotes for air to water and geothermal heat pumps for our new build 1650 sq ft dormer bungalow.(1650 sq ft down stairs)

we had originally thought of putting underfloor downstairs and radiators upstairs however after much research, on this forum, and dealing with suppliers we understand that it would not be a good option.

We will have a high level of insulation and mhrv, a specialist company for air tightness and strong focus on cold bridging.

My question is, is there a need for underfloor upstairs in a dormer as the main living space is downstairs including master bedroom, and has anyone any experience of not putting it in and if so what is the temperature like

Hi Hoofrocks, I was also looking at option of putting underfloor downstairs and rads upstairs, do you mind me asking why you think that is not a good option ???, I am sure you wold need to have some heating source upstairs although it should never be freezing with good insulation and ufh, I suppose it all depends on what level of comfort you require/need. Personally I will def go with some form of heating upstairs, but I am far from an expert.

HoofRocks

gooseygander wrote: »

Hi Hoofrocks, I was also looking at option of putting underfloor downstairs and rads upstairs, do you mind me asking why you think that is not a good option ???, I am sure you wold need to have some heating source upstairs although it should never be freezinog with good insulation and ufh, I suppose it all depends on what level of comfort you require/need. Personally I will def go with some form of heating upstairs, but I am far from an expert.

my understanding is that it is not a good idea to mix a system that runs on a constant low temperature with a system that needs a higher temperature. Having said that I have had suppliers offer this service with alluminium radiators but we won't be going for that.

I want to keep the system as simple as possible.

blast06

I have ~1950 sq ft downstairs and ~650 sq ft upstairs .... UFH heating downstairs, (standard) rads upstairs with same temp water plumbed to them as UFH.
I have the usual air-tightness, masses of insulation, MHRV, etc ...... and as of yet (moved in Aug 31st) haven't needed to turn them on at all (temp has never dropped below 19 degrees upstairs) and never above 21 (too warm at 21 anyway for bedrooms). I finally tried turning on the rads about a week ago to see what the impact was and by the following evening temp was 22 degrees.
So standard rads do work plumbed with same temp water as UFH .... and you'll hardly ever need them anyway (and to think i almost spent an extra grand putting in some low temp rads - brand i can't recall :eek: )

The only caveat i have is that i have a double height front hall so its difficult to say how much of a factor that is but i would guess that it is only the 4th factor for the bedrooms off the upstairs landing, i.e.: insulation, air-tightness and MRHV all complementing one another and filling the top 3 most important factors.

HoofRocks

blast06 wrote: »

I have ~1950 sq ft downstairs and ~650 sq ft upstairs .... UFH heating downstairs, (standard) rads upstairs with same temp water plumbed to them as UFH.
I have the usual air-tightness, masses of insulation, MHRV, etc ...... and as of yet (moved in Aug 31st) haven't needed to turn them on at all (temp has never dropped below 19 degrees upstairs) and never above 21 (too warm at 21 anyway for bedrooms). I finally tried turning on the rads about a week ago to see what the impact was and by the following evening temp was 22 degrees.
So standard rads do work plumbed with same temp water as UFH .... and you'll hardly ever need them anyway (and to think i almost spent an extra grand putting in some low temp rads - brand i can't recall :eek: )

The only caveat i have is that i have a double height front hall so its difficult to say how much of a factor that is but i would guess that it is only the 4th factor for the bedrooms off the upstairs landing, i.e.: insulation, air-tightness and MRHV all complementing one another and filling the top 3 most important factors.

Thanks for your response blast, so given the temperature rose 3 degrees, in hindsight would you put them in if you were doing it again? We too have a double height in the entrance hall

blast06

Hi .... well it would have been more like a 1.5 degree rise (i max'd out the thermostats so that rads didn't turn off at any stage.

If i was doing it all again ...... i can thankfully say i would do the exact same as i have done, i.e: normal rads with UFH water temp plumbed to them

HoofRocks

blast06 wrote: »

Hi .... well it would have been more like a 1.5 degree rise (i max'd out the thermostats so that rads didn't turn off at any stage.

If i was doing it all again ...... i can thankfully say i would do the exact same as i have done, i.e: normal rads with UFH water temp plumbed to them

Was this something you specified with the heat pump company or is that standard practice. I have been told by suppliers that rads upstairs will reduce the efficiency of the heat pump by up to 10%

galwaytt

I have UFH downstairs and rads upstairs, in a dormer, since..............1997. Btdt, have the t-shirt

It's a very simple system I have (given it's age, etc). Boiler with output Tee'd in 3: DHW, UFH and rads, each with motorised valve, and controlled a by a 3-channel, 7-day timer. I have no 'stats in the house, relying on the static valves on UFH manifold, and TRV's on rads. The boiler stat controls the DHW temp.

Couple of things I would suggest you consider:

You need a heat source (boiler etc), that can supply water to the temps the rads require, and easily. Imho this means an easily modulating heat source is what you want. For me it turned out the best solution was a modulating super-condensing gas boiler. An oil burner for example, wouldn't be as flexible to the demands on it, and solid fuel even worse. So the question for you is determined by your rads, not your UFH.

For the UFH the heat source output required will be lower than the rads, so a mixing valve will pull it down.

You don't NEED UFH in a dormer upstairs, but it is nice. Tidy, no rads to locate or furnish around. I built a new house in 06/07 and put UFH upstairs. Being a more modern and efficient house, it actually doesn't need it. Hindsight is a wonderful thing and all that...........

So maybe your choice will be driven by just liking it. Either system works.

As mentioned above, if you buy a modern low-temp water rad the mix of UFH + rads should be even better and smoother, than my old set up.

Either way, it works - but boy is it down to the quality of the plumber................don't get me started !!

The double height hall does bring it's own strange behaviour...........

blast06

HoofRocks wrote: »

Was this something you specified with the heat pump company or is that standard practice. I have been told by suppliers that rads upstairs will reduce the efficiency of the heat pump by up to 10%

No, had no spec agreed with supplier.
Re the efficiency ... I can see why there would be given the lukewarm water in the rads (same temp as in UFH) would cool down quicker than that in the UFH pipes. However, the efficiency would only be a factor IF i ever actually had to turn them on in the first place !!

galwaytt

I think you need to divorce the issue of ASHP/GSHP and method-of-heat-delivery (ufh vs rads), tbh.

The pumps do work better on low-grade heat systems such as UFH. Unless of course, you're heating a buffer tank - are you ?