UFH with Rads Upstairs.

Jofspring

Hi all,

I'm looking for a few opinions. As it stands we are looking at getting UFH downstairs using a heat pump. The issue at the moment is what to do upstairs. The Architect is of the opinion to go with Rads upstairs because if we put down carpet or wood flooring upstairs they will act as insulators for UFH and defeat the purpose of the UFH up there. He feels the engineered wood is really only for warping issues and still blocks the heat. The builder thinks you won't save much with Rads upstairs and that the heat should still be fine coming through.

From what I have been reading though the Heat Pump will be less efficient if it has to heat Rads upstairs also so their seems to be negatives to both options.

The house is a split house with bungalow one side and dormer on the opposite. Concrete first floor also. Size 2,444sqft. MHRV to be installed also.

So basically I have a few questions:

Which is best, UFH up and down or spilt between UFH and Rads?
Will a spilt affect efficiency much?
Will carpet or wood affect the efficiency upstairs with UFH, how have people that have this found it?
Do people find they even turn on the heat upstairs much so it's fairly irrelevant which you go for?

I will be going for prices in the next week so want to have a bit more knowledge before I start to search and have questions coming at me.

Any help would be appreciated.

Calahonda52

The issue with rads off a HP is the delta T coming off the rads with a low temp water input
https://www.aelheating.com/how-to-calculate-delta-t/
If the rads are big enough then they will work but my guess SWMBO will not be impressed with long rads

If you go with normal rads, whats the heat source?

Just for curiosity, whats the house construction plan for the walls and what is the Air T target?

Dudda

I’d go with UFH upstairs. If you’ve a concrete first floor you’ll have some type of screed so have the UHP in that. The heat will pass through the floor finish as long as it’s not a very heavy carpet with a high tog. You can just look out for this when selecting a carpet. Similarly most timber floors are fine at a lot UFH temperature. Usually you need less heat upstairs anyway. Assuming the house is very well insulated and airtight the heat from the lower level will rise and the MVHR will help distribute the heat around the house. Additionally while 20-22 degrees is required downstairs for the average person bedrooms can be as comfortable in the 18-20 degree range. It’s very hard to sleep in a bedroom that’s to hot and dormer bedrooms can heat up a lot.

Jofspring

Calahonda52 wrote: »

The issue with rads off a HP is the delta T coming off the rads with a low temp water input
https://www.aelheating.com/how-to-calculate-delta-t/
If the rads are big enough then they will work but my guess SWMBO will not be impressed with long rads

If you go with normal rads, whats the heat source?

Just for curiosity, whats the house construction plan for the walls and what is the Air T target?

The heat Pump would be used to head both the UFH and rads.

I don't know exactly what the Air T target is. When discussed a few months ago with the Architect he was saying we should be aiming for a target of around 1 and that on most builds he was involved in they have been getting well under 1. That sound about right?

From looking at the BOQ I can see 150mm cavity with 150mm bonded bead cavity insulation. Floor insulation, insulation between the rafters. Airtightness tape around all windows and external doors and also at junctions of ceilings and external walls.

recedite

Dudda wrote: »

Additionally while 20-22 degrees is required downstairs for the average person bedrooms can be as comfortable in the 18-20 degree range. It?s very hard to sleep in a bedroom that?s to hot and dormer bedrooms can heat up a lot.

True, but wouldn't that be a good reason not to have UF in the bedrooms. It would be like sleeping in a room with electric storage heaters on.

Anyway the issue in simple terms is that the water in the rads supplied by a heat pump would not be as hot as in rads supplied by a gas boiler. But if the house is well insulated, and bearing in mind that heat rises, the lower rad temp. should not matter.
Also you can get aluminium rads and rads with in-built fans that throw out the heat more than standard ones.
Rads upstairs also have the advantage that you can fit TRV's to them, and so turn down the heat in each room to suit individual room usage.

Borzoi

Jofspring wrote: »

Hi all,
The house is a split house with bungalow one side and dormer on the opposite. Concrete first floor also. Size 2,444sqft. MHRV to be installed also.

So basically I have a few questions:

Which is best, UFH up and down or spilt between UFH and Rads?
Will a spilt affect efficiency much?
Will carpet or wood affect the efficiency upstairs with UFH, how have people that have this found it?
Do people find they even turn on the heat upstairs much so it's fairly irrelevant which you go for?

I will be going for prices in the next week so want to have a bit more knowledge before I start to search and have questions coming at me.

Any help would be appreciated.

we've a similar sized house with a floor plan that's 2/3 ground floor and 1/3 first floor for bedrooms and an ensuite. we have UFH throughout and the upstairs heat is barely used with exception of the ensuite when it's really used to take the chill off the tiles😀

by it's nature UFH is slow response. whether wood or tile (we've no carpet)

zulutango

Jofspring, are you aiming for a particular BER rating for the house? I would advise that you put a lot of effort into trying to achieve a high rating, and if you do, then your heat load upstairs will be quite low and that could influence the decision. I would probably go with some form of electric heating in that situation, and realistically you wouldn't require it all that much. If it's a lower BER I'd go with rads. Underfloor heating and lower BER homes are not well matched because the underfloor heating (because it holds heat in a thermal mass, i.e. the screed) can't adjust to fluctuations in the outdoor temperature. It ends up being inefficient as a result. It would mean that you will need bigger rads though. Alternatively, you could have a gas boiler to top up the flow temp in the rad circuit and use the heat pump to preheat the water.

Jofspring

At the moment I'm being told we are looking at a BER of A3. The Architect has sent the details out to get the provisional BER so I'm just waiting to get that back. I should have it next week and I'd imagine I will know better from there.

I talked to a company from Cork last week about prices etc... and they said it wouldn't save me any money if that's what I was looking at. He was of the opinion that the having the concrete floor upstairs to go for under floor. I'm waiting for quotes back from 3 other companies so will see what opinion I get from there.

The only thing I keep hearing from the wife is "sure where will we dry the clothes if we have no Rads"