UFH house seems cold

Dan Robinson · 16 Dec 2018

You probably will need the water at 45 degrees going into the floor with 40 coming back to the manifold.

The valve appears to be set to 50.

If the flow and returns to the manifold are at 60 or so, then the blending valve is guffed.
You cod try temporarily removing the capillary probe from the manifold above the pump and see if that helps.

dk1uk · 16 Dec 2018

I don’t have a thermometer to check, but to the touch, the flow out and the return are definitely different temperatures.

I’ve tweaked the flows a bit on some of the loops to increase the flow to see if it makes a difference. The landing is very open with a floor to roof open void so that’s going to be difficult to keep warm so maybe I’ll never solve that one.

The bedrooms are the most problematic - could that we the carpet??

I notice on the downstairs manifold there’s a Wilo pump which is set to max speed. On the upstairs manifold there’s a Lowara 7-speed pump, which is on speed 6. Is switching it to 7 likely to help (if it is indeed the carpet limiting the heat coming through)?

Gasguru · 16 Dec 2018

It might be worth you contacting Emmeti in the UK to see if they can recommend anyone nearby.Randomly fiddling with pump speeds, TMV heads could make things worse. There's also a flow valve just above the TMV head that requires setting too....and this has an influence on the top rail temperature. Does the boiler get up to high temperature?

dk1uk · 16 Dec 2018

Yes the boiler gets up to a high temp. As do the top rails on the upstairs and downstairs manifolds.

Gasguru · 16 Dec 2018

The picture you posted shows a temperature of only 35 degrees...it's normal to run at 45 to 50 degrees.

dk1uk · 16 Dec 2018

Ah I see. Just taken a pic of the gauge on the upstairs manifold and it’s running at closer to 50 now (some loops are calling the boiler).

The downstairs manifold is in the second pic below running at 35 (no loops currently calling the boiler).

snb · 16 Dec 2018

Change timings so underfloor is on 24hrs. Will make a huge difference. Normal for upstairs flow,to be set at 50 as probably spreader plates, and ground floor at 35 to 40 as it will be screed.

dk1uk · 16 Dec 2018

Just checked and upstairs there is only one loop calling for heat. Earlier this morning when I posted the temp pic, several loops were calling for heat, could it be that the temp drops when it’s under greater demand?

dk1uk · 16 Dec 2018

snb said:
Change timings so underfloor is on 24hrs. Will make a huge difference. Normal for upstairs flow,to be set at 50 as probably spreader plates, and ground floor at 35 to 40 as it will be screed.

It’s normally on 2am to 10pm so almost 24 hours. Tweaking the flow for one of the downstairs rooms has brought it up to 20 degrees for the first time since the weather cooled.

snb · 16 Dec 2018

On the flow meters with all loops demanding downstairs adjust so you get about 2.5lt flow min on each. Upstairs manifold will need closer to 3 if that's possible with all open

dk1uk · 16 Dec 2018

snb said:
On the flow meters with all loops demanding downstairs adjust so you get about 2.5lt flow min on each. Upstairs manifold will need closer to 3 if that's possible with all open

Thanks, will give that a try. On both manifolds is a pink sheet left by the installer where they’ve written flow rates anywhere between 1.9 and 0.5. Unless there’s another problem, these flow rates are clearly not enough and the date on the sheet is 10th Oct 2016 - would it have made a difference that he/she made these adjustments when the weather wasn’t too cold?

dk1uk · 7 Jan 2019

I’ve been able to spend some time again looking at this and something I’ve noticed.

Even though the UFH heating loops have been calling for heat all day, the boiler fires up to about 70c, then stops firing and the temp drops to about 38c and keeps repeating the loop. Each cycle takes about 4 minutes.

It’s as if the boiler can’t maintain a consistent temperature. I don’t know if this is a boiler fault or whether the UFH is causing the boiler to behave this way.

Does anyone have any ideas of how to check please?

Dan Robinson · 7 Jan 2019

Possibly a case of the boiler being grossly oversized and with totally inadequate modulation ratios.

What power rating is the boiler? What sort of heat requirement does the house need?

Does the boiler and UFH perform better when the cylinder is recharging from near cold?

dk1uk · 7 Jan 2019

Thanks Dan. I’m afraid I’m not so technical as to be able to answer those questions. However, it’s a new build house and my neighbour has exactly the same house with boiler and UFH. He popped round, I showed him the boiler firing up and down in temperature and he confirmed that his boiler doesn’t do this, it reads 68c consistently.

So I’m guessing that mine has a fault or something has been set up incorrectly

Dan Robinson · 7 Jan 2019

The boiler is probably not broken, however, there is a flow rate problem.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

UFH house seems cold

Similar threads