UFH not working consistently well

Hardware Heatpump
1

Hi, I have a random question with regards to the output of my UFH. I had a Daikin Altherma3 8KW installed in my Victorian terrace. The system as such works (hot water, also zone heating as such), but the UFH doesn’t seem to manage to heat up all areas well enough during the winter. The parts of the house with wooden floor boards is absolutely fine, but the bits with either tiles (kitchen/bathroom) or engineered wooden floor (UFH compliant) are struggling. When the builders installed the UFH, they couldn’t use spreader plates because of the space available between the joists, so they put insulating kingspan boards underneath to reflect the heat.

I’ve already moved the WD upwards, and I’ve reduced the flow rate in the affected rooms, but it only had a tiny effect. Does anybody else have a similar problem, and/or any advice/suggestions?

Many thanks for your help!

2

What does the manifold look like? Is the water definitely circulating in those loops?

3

Assuming you are open loop with no mixer and additional pump.

Open all flow meters fully on the manifold. Let run for a day. If you have rooms too cool the heat pump flow temp needs to increase. Get the cool areas up to the temperature you need via heat pump. To get rooms that are too warm cooler you trim back the flow rate at the UFH manifold.

If you have mixer and pump (because you have radiators elsewhere) you need to do some thing similar to above, assuming pump is set to suitable speed. You no alter the mixer temp rather than heat pump temperature initially.

Generally lower the flow rate through a loop give a wider dT across the flow and return, this gives a lower floor output. Increasing flow rate does the opposite.

4

If the loop pipes are not in close contact with the floor you could end up heating an airspace and very limited heat makes it’s way upwards. You may never get suitable performance, so be prepared. Try what I said above before you panic. But a drawing of what you have may help identifying issues

5

Your differences are interesting.

Floorboards okay

Tiles/engineered wood struggling..

We have UFH downstairs solid screed floor + tiles and these heat up very well and transfer the heat to the rooms best.

Then there’s one room also with screed but it has carpet. This room is a problem.

These are all on the same manifold. Each room is zoned with flow adjustment.

Large spaces have 2 zones.

The carpet room was always 1 - 2°C below the tiled rooms in ambient temp.

Tried all different flow settings on the manifold..

Strangling the tiled rooms flows and opening up the carpet room flow was best.

I even took the lowish tog underlay out, this improved things. To pretty much parity. But with the offset flows still!

So we live with a hardish floor with carpet.

Plan is to wood effect tile or equivalent ceramic floor that room eventually.

Upstairs we have low tog underlay and low tog carpet. No complaints. I guess the heat rising from below and the probably lower output through the carpet works well enough.

Your situation seems kind of the reverse to this and not what I would expect, all things being equal.

Engineered wood should be comparable to thinner wood floorboards (depends on thickness and tog though).

Do you have an IR heat gun or IR camera attachment on your phone so you can see what’s going on?

You can see the UFH loop spacings with the camera. Are they all the same?

As others have said, have a play with the flow rates to achieve parity if possible.

Good luck and let us know how you get on.

6

Hi, The timber floor design can range from a Type B or Type B2 for suspended wooden floors. I guessed you operate with a mean flowing water temperature of ~45C.
If that’s reasonable, then the heat output from your wooden flooring is 76W/m2 when you have close contact aluminium heat transfer plates to the wooden floor. However, the choice of engineered wood/ ceramic tiles with the aluminium foil lined void space drops the heat output to 45 W/m2. This may be similar to your kingsman reflector space. A difference of 60%.
That may explain the cooler floors from a change of the design details during construction.
It is worth testing the flow you deliver to different rooms, since you can still re-balance the heat output to each room and get that “ sweet spot”. I suspect you now need to make bigger manifold flow adjustments to accommodate the different floor designs. This should be based around your original design calculations, but adjusted to recognise your actual floor build. As a rough guide. I think your choice is to increase the flow to the cooler rooms by 60% from the original design calculations. Hopefully you can adjust your manifold flow valves to test it out on a cold day.
Good luck, Frank