Operating Underfloor Heating

[BlueLoo]

@Exedon I found these images of the insulation and underfloor pipes being laid. Any thoughts?

Is that a suspended wooden floor?
If it is, does it have a void below to allow airflow underneath it (As in air bricks/vents, etc).
My understanding is that it should have, to stop dry/wet rot (i am not a builder)

If so, and it has airflow under it, then the UFH has to heat both the above and the below spaces which is asking a lot.

 

[Exedon]

The pipe length you give looks like 200mm spacing as we assumed. If this was a straight forward screed system at 55c you should get around 2100w with a floor temperature of 27.2c
This assumes correct screed thickness and correct installation.
However you have 2 thickness of timber in way which accounts for your low floor temperature which obviously equates lower room temperatures. Working backwards from your floor temperature floor output could be as low as 1400w
Ive quickly run heat calculations a lot of assumptions (I have serious doubts about quality your builders work)
Looking like to achieve 21c heat loss would be around 2.6kw

 

[nirish]

@Exedon I genuinely think the build quality is up to scratch. There have just been some oversights around the heating but I believe the rest is as expected.

It's a joisted floor so I'm not sure how a deep screed system would have worked. I just wish someone had calculated heat losses and explained a better way the floor could have been laid. Whether this would have been enough still sounds debateable.

Anyway I had used this site and come up witj heating requirement of 4000W !!
https://www.plumbnation.co.uk/heating-calculator

Hard to be sure how far short I am, hoping an additional 1k or 1.5k will suffice. I have a 1500W electric fire so planning to run that on the next really cold day to see if it makes up the difference!

Then ideally I'll get a large rad plumbed in off the underfloor return if that's at all possible so bring some of the heat above floor level!

 

[nirish]

@Exedon I've used a few different online calculators for room heat loss which all suggest about 4000W for our room. Can I just double check that you feel 2600W is accurate from your perspective as these numbers are surprisingly far apart. Thanks, appreciate your help!

 

[nirish]

@Exedon based on the pictures do you feel the given pipe length of 55m is likely to be correct? I count 28 runs of pipe approx half the room width (approx 2.5m x28 = 70m)

Basically I'm wondering about flow rate which the internet advises to be Pipe Length / 40.

I have the flow rate set to max 4L/min but am suspicious it's too high as the room temp rises rapidly by a couple of degrees when it's switched off which seems strange. As if stopping the flow allows heat to dissipate?