Noddy2021 Posted January 14, 2021 Share Posted January 14, 2021 hello everyone, First, just wanted to say hello as I am new to the forum. Been reading here a lot recently and look forward to become part of this community ! Bit of background... About 1.5 years ago I moved into my new house that I bought and renovated the year before. Downstairs we put a wet UFH systems and rads upstairs. The ufh pipes are covered by 75 mm of screed and then having engineering wood glued on top. Unfortunately the plumber (who was sub contracted by the builder) proved to be very incompetent. Long story short I kicked him out, etc. After a few different plumbers, we managed to get the underfloor heating working. It has performed very well so far and I am pleasantly surprised by the low gas bills... ONE SLIGHT ISSUE - Sometimes when I come downstairs in the morning I notice that the floor is very hot. I went on amazon and purchased one of those infrared thermometers. It showed 30/31 degrees in some places. I remember hearing that 27 should be the max and so my investigation began... After much googling around I read somewhere that I need to look at the manifold temperature/blending valve. This was set on 55 Degrees. Why? I have no idea that's how the plumbers left it when I first moved in. I have turned this down right down to 37/38 degrees and my floor surface temperature is now 26/27 degrees. My questions: Is this the right way to run UFH? Will I be spending more given the low manifold temperature? Will be boiler be constantly on as my ufh will be keeping the house warm with low manifold temperature? Just want to make sure I haven't done anything to potentially do harm to my system... Link to comment Share on other sites More sharing options...
ProDave Posted January 14, 2021 Share Posted January 14, 2021 Yes you don't want the UFH that hot, it will damage the wooden floor. We are probably at the coldest part of the year, so keep turning it down each day until you reach a point it won't heat the house properly, then turn it back up a little. Link to comment Share on other sites More sharing options...
PeterW Posted January 14, 2021 Share Posted January 14, 2021 @Noddy2021 you have done the right thing. I would tweak it to 40°C flow at the moment and bring it down a bit assuming you’re hitting the target room temperature. If you find you aren’t then extend the programme run time first before you change the temperature up. Link to comment Share on other sites More sharing options...
Noddy2021 Posted January 14, 2021 Author Share Posted January 14, 2021 Thank you very much for your answers! My boiler temp is and has been set at 75. Do you think I should leave it on that or lower it? Link to comment Share on other sites More sharing options...
A_L Posted January 14, 2021 Share Posted January 14, 2021 28 minutes ago, Noddy2021 said: My boiler temp is and has been set at 75. Do you think I should leave it on that or lower it? Assuming this is a modern condensing gas boiler turn the flow temperature down to a maximum off 60°C so that the return condenses the flue gases, which occurs at about 57°C. This gives 10-15% more heat from the same amount of gas. Link to comment Share on other sites More sharing options...
Chriswills Posted January 14, 2021 Share Posted January 14, 2021 I’ve been experimented with my temps over the last few weeks. Although I have an ASHP, I have UFH downstairs and rads upstairs. It only does heat and not DHW. I was outputting 50 deg C and bills were huge. Now turned it down to 35 and set zones to 18. UFH is great and so are rads. I did fit a radfan to the coldest room and this has made a difference. If I was you, keep turning everything down until you are comfortable. I was doing a change every 24 hrs. Link to comment Share on other sites More sharing options...
Noddy2021 Posted January 14, 2021 Author Share Posted January 14, 2021 I see. My room stat is set at 25 and I never turn it down 24hrs a day.... I know some will say that's hot but kids feel colder on anything below that... My gas usage for December was £115. That's an actual reading not an estimate. Link to comment Share on other sites More sharing options...
PeterW Posted January 14, 2021 Share Posted January 14, 2021 That’s very warm ..!! I’d get the kids some jumpers ..!! Try it down by a couple of degrees and see what happens. 1 Link to comment Share on other sites More sharing options...
joe90 Posted January 14, 2021 Share Posted January 14, 2021 My kids grew up in a house cooler than that, 21’ max, and I grew up in a house much colder than that. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 15, 2021 Share Posted January 15, 2021 Mine is currently running at 50C+ boiler temperature to keep the place reasonably warm (20C) whilst outside temps are just above zero, But my walls are 0.2 u value ish (floor 0.18) which is too poor, but not built by me. My problem is emitter area and not enough insulation under the ufh. Not much can be done easily, though. Total energy bills are not that horrible for a 200 sqm house, but I don't like it. F Link to comment Share on other sites More sharing options...
Ferdinand Posted January 15, 2021 Share Posted January 15, 2021 7 hours ago, Noddy2021 said: hello everyone, First, just wanted to say hello as I am new to the forum. Been reading here a lot recently and look forward to become part of this community ! Bit of background... About 1.5 years ago I moved into my new house that I bought and renovated the year before. Downstairs we put a wet UFH systems and rads upstairs. The ufh pipes are covered by 75 mm of screed and then having engineering wood glued on top. Unfortunately the plumber (who was sub contracted by the builder) proved to be very incompetent. Long story short I kicked him out, etc. After a few different plumbers, we managed to get the underfloor heating working. It has performed very well so far and I am pleasantly surprised by the low gas bills... ONE SLIGHT ISSUE - Sometimes when I come downstairs in the morning I notice that the floor is very hot. I went on amazon and purchased one of those infrared thermometers. It showed 30/31 degrees in some places. I remember hearing that 27 should be the max and so my investigation began... After much googling around I read somewhere that I need to look at the manifold temperature/blending valve. This was set on 55 Degrees. Why? I have no idea that's how the plumbers left it when I first moved in. I have turned this down right down to 37/38 degrees and my floor surface temperature is now 26/27 degrees. My questions: Is this the right way to run UFH? Will I be spending more given the low manifold temperature? Will be boiler be constantly on as my ufh will be keeping the house warm with low manifold temperature? Just want to make sure I haven't done anything to potentially do harm to my system... One question there is how much insulation is *under* the UFH. But that will not affect how you need to run it now as it is a sunk cost. It needs to be ideally about 125mm of PIR or 250-300mm of EPS. The chap who did my house just did 90mm of PIR, down there 10-12 years ago and I do not know really how good the attention to detail/cold bridges was down there. Link to comment Share on other sites More sharing options...
Noddy2021 Posted January 15, 2021 Author Share Posted January 15, 2021 (edited) I have quinn therm 100mm all over the floor. The house is covered in a silicon based render and has 100mm insulation around. Typical I lose 1 degree over night with heating off so not too bad. Edited January 15, 2021 by Noddy2021 Link to comment Share on other sites More sharing options...
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