Underfloor heating - not warm!

[yermer]

We had water underfloor hearing installed both upstairs and downstairs when we had our house refurbished but it just doesn’t seem to work effectively. The boiler is on max (70 degrees) and the only room we can get to 23 degrees is our kitchen (with concrete slab beneath). The rest of the rooms top out at between 19 and 21 degrees and that’s after being on all day which doesn’t seem right.

We’ve had an experienced plumber out and he says the next step is to pull up floors to check the insulation but I can’t help feeling it’s not (just) that as even the kitchen (with new concrete slab floor) doesn’t get super warm. Does anyone have any thoughts on this? We’re desperate not to pull up floors if at all possible. .

Not an expert but I would switch off the warmest room and see if you can get the other rooms warmer. That might give some clues.
I presume you’ve checked thermostats aren’t limiting it.

UFH is not supposed to get hot. It should feel comfortably warm when you walk across it barefoot, or when your cat sleeps on it. The heat balancing and thermostatic controls need a person skilled with setup and I have no knowledge of how to do it. In frosty weather, houses are often rather cool if the heating installation was a bit meagre. If you have the original plan and quotation you could get an experienced person to look at it to see if it seems adequate.

You can work out how much heat is going into it by observing the gas meter.

It is a lot of work to pull up the floors and look at it. Can you improve insulation and draughtproofing in the affected rooms? This will make them warmer.

Are you keeping all the internal doors shut during the heating season?

Is your hot-water cylinder surprisingly hot?

Due to the temperature exchange and the floor covering the heating, if it's too hot, then that could lead to a hazard based on the materials used ect,

We leave our ufh on 24 hrs a day. If temperature drops its usually due to an airlock or water pressure in boiler has reduced, both simple to resolve.

23 degrees is hot. We have ufh and set to 21. It’s just a constant warmth. Water doesn’t get heated to over about 65 degrees on most systems. Do you have it correctly installed? What is covering the floor?

You don’t really turn it on and off. It’s a constant heat and 21 degrees should be fine.

Get in touch with the people who Installed/commissioned it. It is possible your settings are just slightly out. We built our house summer 2019 and it took about a year for us to get the settings right eg the living room was always cold if the wind blew a certain direction now it’s fine. 23 is quite warm for the room itself but if you mean the water is 23 maybe that’s a bit low. I wouldn’t start ripping the floor up just yet contact the company who installed it.

@yermer
Some of what you say would worry me about the installation. The installer should have discussed with you before installing it the need for underfloor insulation and downstairs several inches of if to stop you heating the ground. If they haven't done that then they may not be that knowledgable in UFH installation and apparently many plumbers and gas engineers are not. We had it installed in our new extension build and in parts we have it set to 24 degrees (I feel the cold although DH thinks I'm wanting to grow tropical plants!)

Ours took a little adjusting to get right. The boiler being at 70 is not relevant to the UFH (is to the rest of the system). There is a blending valve that mixes the water coming from your boiler with cooler water before pumping it around the UFH pipes. The maximum we can set our valve to is 55 degrees but in practice this is too hot and is not recommended or comfortable underfoot. Somewhere between 30-45 is probably about right but depends on your flooring and loss of heat (if no insulation!).

The other control to be aware of is the flow meter for each circuit. These can be set to slow or increase the flow of water. A longer circuit you need a faster flow or else by the end of the loop the water will be cold. I can't recall what the flow should be as we haven't needed to adjust it.

I would have a look and also speak to the installer. Ripping up the floor is ridiculous and extremely expensive. If he hasn't installed with the right insulation it is questionable if it has been undertaken to a satisfactory standard and you may need to get some legal advice.

I knew nothing about UFH before we had our extension but it is lovely and warm...even at minus 8 degrees last week we were basking (or I was) at a constant 24 degrees and the control is sensitive and keeps it dead level at that

It is different though to standard radiators and needs a lot longer to warm up. Conversely we also have it switch down a lot earlier...6 pm on an evening ours go off as the heat lasts for ours, but it comes back on at 3 am

Hope that helps