Biggiebig Posted January 18 Share Posted January 18 hi, I've had UFH downstairs over 10 years and been please with it. In the summer it was installed upstairs and now rooms are struggling to get to a decent temperature. Here are the details : Property: 1930s semi. Exterior foam installation at the front. Rear and Side comply to recentish building regs having the house renovated within the last 10 years. Loft installation is decent with double layer. Windows double glassed replaced (Rear recently, Front 10 years ago). Boiler: Powerful Valiant Gas Boiler Upstairs UFH System: 6 Zone manifold , installed with auto airvent, pump , and mixing valve, thermostat on incoming , Tado thermostats in each room UFH installation: On existing floorboards > Foam underlay boards > 15mm poly pipe > Aluminium Foil on top > 20mm ply > UFH underlay < wool carpet (2.5 tog) Flow Rate: Set between 2-4 (i've tried varying these but no joy) The bedrooms temp vary from 18 deg (Max) with two bedrooms not exceeding 17 deg and 15 deg in very cold weather. This is in cold weather and temp set to 50 deg. Boiler is set to 60 deg flow. I've tried quite a few things like messing around with flow rates and even flushed the system incase it had air but no joy. My bills are insane atm as i'm keeping the system on 24/7 and boiler/pump is always running as rooms don't get to temp. Not having the ability to not have toasty rooms concerns me and i'm worried there's something fundamentally wrong with the installation e.g plywood too thick or wool carpet trapping the heat. All the bathrooms seem fine as the floor is warm but bedrooms seems to struggle. ATM my only option is to revert to AC heatpump for backup secondary heating. Link to comment Share on other sites More sharing options...
Lofty718 Posted January 18 Share Posted January 18 Something seems very wrong here, UFH shouldn't need to be run at 50c what is your downstairs UFH running at? Mine is running at 38c in this current weather Post a picture of your manifold setup. How many kwh of gas are you using a day? Link to comment Share on other sites More sharing options...
Biggiebig Posted January 18 Author Share Posted January 18 (edited) The coldest bedroom is 14.4 and heating has been on all day floor is cold. could it be heat loss can’t see where as even when you enter the room floor is cold to touch. Could it be the ply/carpet not letting heat up. I just removed a spot light from downstairs and shifted the insulation to the side the floorboard is slightly warm to touch but guess this is expected. Edited January 18 by Biggiebig update Link to comment Share on other sites More sharing options...
Biggiebig Posted January 18 Author Share Posted January 18 The aluminium foil has been laid on top of the pipe could this be preventing the heat from coming up ? Link to comment Share on other sites More sharing options...
Biggiebig Posted January 18 Author Share Posted January 18 33 minutes ago, Lofty718 said: Something seems very wrong here, UFH shouldn't need to be run at 50c what is your downstairs UFH running at? Mine is running at 38c in this current weather Post a picture of your manifold setup. How many kwh of gas are you using a day? Down stairs is also around 50 but I have a thick slab of concrete so it take a while to come up other wise. i'm currently using around 190 KWH in very cold weather (south west) for a 2300 SQ FT house. Link to comment Share on other sites More sharing options...
JohnMo Posted January 18 Share Posted January 18 28 minutes ago, Biggiebig said: Could it be the ply/carpet not letting heat up. Bedrooms are they underlay and carpet? We had UFH in a summerhouse under OSB and laminate floor, never got warm Link to comment Share on other sites More sharing options...
Biggiebig Posted January 18 Author Share Posted January 18 1 minute ago, JohnMo said: Bedrooms are they underlay and carpet? We had UFH in a summerhouse under OSB and laminate floor, never got warm Yes underlay and carpet the underlay (special for UFH) from memory the combined tog is 2.6 Link to comment Share on other sites More sharing options...
Lofty718 Posted January 18 Share Posted January 18 I'm in a similar sized house (2100 sqft) but using 160kwh per day heating whole house to 21c 24/7 got rads upstairs rather than ufh though. I notice your pump speed is on number 3, this is a bit high try and put it on number 1 and see what happens also your flow meters are all over the place some reading very high. On the gauge on the UFH manifold what flow and return temperatures are you getting? are all the pipes evenly hot to touch? also what boiler do you have and how is it controlled? Link to comment Share on other sites More sharing options...
JohnMo Posted January 19 Share Posted January 19 12 hours ago, Biggiebig said: The aluminium foil has been laid on top of the pipe could this be preventing the heat from coming up ? Aluminium is a conductor, so would not prevent heat transfer, it will actually even out the heat. Link to comment Share on other sites More sharing options...
JohnMo Posted January 19 Share Posted January 19 (edited) 12 hours ago, Biggiebig said: Down stairs is also around 50 but I have a thick slab of concrete so it take a while to come up other wise. So how are you operating your heating, a batch charge once a day or on all the time? Edited January 19 by JohnMo Link to comment Share on other sites More sharing options...
Andehh Posted January 19 Share Posted January 19 Are the pipes all warm to the touch leaving and entering the manifold? Is there any temp difference between flow and return? Buy an IR thermometer for £10 and check each rooms. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 1 hour ago, JohnMo said: So how are you operating your heating, a batch charge once a day or on all the time? Down stairs is a 3-4 hour boost which works well as the concrete heats up and gives us a toasty 20-21 for 24 hours upstairs as temperatures aren’t being reached it pretty much runs 24/7 Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 9 hours ago, Lofty718 said: I'm in a similar sized house (2100 sqft) but using 160kwh per day heating whole house to 21c 24/7 got rads upstairs rather than ufh though. I notice your pump speed is on number 3, this is a bit high try and put it on number 1 and see what happens also your flow meters are all over the place some reading very high. On the gauge on the UFH manifold what flow and return temperatures are you getting? are all the pipes evenly hot to touch? also what boiler do you have and how is it controlled? thanks had pump on 1 last night and all flow rates at around 2 with mixer at 40. temps in bedrooms range from 15.5 - 17.5 and have been running all night using 70kwh of gas. so still no real difference I’ve changed the pump speed to 2 now. yeah both outgoing pipes hot out and warm in. I’m getting a IR thermometer today so will report back when I can measure. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 I’m getting increasingly worried that the ply/carpet have a very low thermal conductivity letting no heat through. As it stands it’s pretty useless as heating and costs a packet to run. I do wonder where all the heat energy is going.. Link to comment Share on other sites More sharing options...
Conor Posted January 19 Share Posted January 19 46 minutes ago, Biggiebig said: I’m getting increasingly worried that the ply/carpet have a very low thermal conductivity letting no heat through. As it stands it’s pretty useless as heating and costs a packet to run. I do wonder where all the heat energy is going.. Out the walls and up through the roof. Give us an overview of your insulation, glazing etc. You're burning a lot of gas. The heat is going in to the house. Then it's leaving at a rate too high to let your rooms get to comfortable temp. It's nothing to do with your carpet. Link to comment Share on other sites More sharing options...
AliG Posted January 19 Share Posted January 19 I have this kind of system installed in our kitchen with a tiled floor in our last house. Basically it doesn't work very well. A wooden floor cannot transit anywhere near as much heat as a concrete floor. Add the insulation from a wooden carpet on top and you will just make things worse. Also with no insulation below the pipes and effectively insulation above the pipes in the form of carpet the heat could be disappearing into the ceiling void if it is draughty. We had a timber frame house built in the 90s and I had to set the flow to the 50s in the kitchen to keep the temperature up when it was cold outside. In contrast two radiators had worked perfectly well to keep the room warm. The easiest thing to do to see if it is the floor would be to lift the carpet in one room if you can and see if it gets warmer. 190kWh is not a shocking amount to use when temperatures are below 0 for that size and age of house. The fact that you are running 50C flow downstairs suggests that your insulation is not that good. We run our flow in the high 30s/low 40s depending on the flooring in the room. Link to comment Share on other sites More sharing options...
JohnMo Posted January 19 Share Posted January 19 45 minutes ago, AliG said: The fact that you are running 50C flow downstairs But only for 3 to 4 hrs. Our garden room floor was similar buildup but with laminate flooring, was just rubbish at heat transfer. Probably better just switching the bedroom UFH off and opening the bedroom doors. Run the downstairs longer to compensate. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 Insulation is pretty good Most of the rear of the house has been rebuilt to modern build reg (last 12 years) The front has External cladding wrapped around and we have double loft insulation. So even though not perfect the insulation isn't terrible. The UFH is on XPS foam boards followed by old wooden floor boards and then insulation between the joist. I have removed lights and speaker from downstairs and no obvious heat escape. When we have a box on the carpet then it does appear to be very warm underneath and under the beds seem warm just the floor doesn't get to Temp. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 Downstairs not sure why we run at 50 just have done for 10 odd years and kind of use to it we have 100mm celotex boards followed by 80mm concrete and engineered wood and downstairs never had any issues. I will try running at low temp for longer periods and see if it works better downstairs. Also I have changed the setting on the pump for proportional to constant as it was set incorrectly i'll check if that helps. What speed do people recommend remember it's quite a large floor arear Link to comment Share on other sites More sharing options...
JohnMo Posted January 19 Share Posted January 19 29 minutes ago, Biggiebig said: What speed do people recommend Keep turning it down until the flow rates start to drop from their set point on the manifold flow meters. If it's a big drop one speed up. I have same number of loops, same pump on speed one - no issues with flow rate. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 Right got my temp gauge now measurements of my upstairs pipe Strange - It's was showing 44 deg for incoming and around 6-8 deg lower for return so all looks good then mixing temp drops Now outgoing pipes show 34 deg and return shows the same may be 1deg difference in some cases Not sure why the sudden fluctuation Floors are showing 20 deg with the gun and then my cold spare room which barley gets to temp suddenly drops to 16/17 deg Link to comment Share on other sites More sharing options...
Biggiebig Posted January 19 Author Share Posted January 19 Just checked again the the temps back to 44 out 33 return on most zones. Wonder why I don't get this delta at lower temps, wondering if I need Salus actuators would it make any difference ? Link to comment Share on other sites More sharing options...
AliG Posted January 20 Share Posted January 20 The heat output is proportional to the floor temp. If the floor is only getting up to 20C then it is not warm enough to heat the rooms. It usually needs to be around 27C. If you look here you can see how the heat output varies depending on the floor buildup. You could be as low as 30-40w/sq metre which probably isn’t enough. https://ambienteufh.co.uk/app/uploads/2021/10/Ambiente-HeatOutput-Table-Doc-21.pdf The fact that the return temp is lower than the flow temp shows that there is heat input but it is being lost. Link to comment Share on other sites More sharing options...
Biggiebig Posted January 20 Author Share Posted January 20 So overall I’ve come to the conclusion that I will have to run at high temps to warm rooms up. Link to comment Share on other sites More sharing options...
Andehh Posted January 20 Share Posted January 20 (edited) If in doubt.... More clout! (and beef up the insulation elsewhere, where you can... Roof? External? Draft proofing?) Edited January 20 by Andehh Link to comment Share on other sites More sharing options...
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