AsankaG Posted January 25, 2023 Share Posted January 25, 2023 Hi All, Hope I could get some advise and where to look for solutions. Moved into a newbuild recently and having some issues with getting heating working as we would like. The other neighbours in the building are also experiencing the similar issues as us. The issues we have are that rooms take a long time heat up. It averages about 60mins per 1c increase and it seems to hit a brick wall around 20c. In December last year it was struggling to go beyond 18c. Heating system info below: Greenstar CDi Compact Combi Boiler Wall-mounted K1 Single Panel Radiators (800x600mm)(721W/m | 2487 BTU/hr) All radiators plumbed individually. What I have done so far: Bled all the radiators. Had TRVs on MAX for extended period of time. Lockshield valves were fully open on all radiators so tried closing them by a few turns on each. I've got a thermal camera just to see if there were any issues and I've included the pictures of these radiators with this post. I'm not sure if this normal way of heating for single panel flat radiators. The middle bottom part is generally warm to the touch. What I'm trying to figure out is if the issue is with radiators or if the radiators are undersized for the rooms (bedrooms - 3mx4m; 1x radiator each, living/kitchen - 8.4x3.4m; 2x radiators) or if there's a balancing issue. Any help and guidance would be appreciated. Thanks Link to comment Share on other sites More sharing options...
JohnMo Posted January 25, 2023 Share Posted January 25, 2023 What is your flow temp setting on the boiler? Link to comment Share on other sites More sharing options...
AsankaG Posted January 25, 2023 Author Share Posted January 25, 2023 14 minutes ago, JohnMo said: What is your flow temp setting on the boiler? Hi, The temp at the boiler is set at 72c. I'll update this figure on the OP as well. Thanks. Link to comment Share on other sites More sharing options...
Radian Posted January 25, 2023 Share Posted January 25, 2023 13 minutes ago, AsankaG said: The temp at the boiler is set at 72c. I'll update this figure on the OP as well. That's quite surprising. I had guessed it was going to be set to 55oC. Is it 10mm pipework back to a manifold for each radiator? Link to comment Share on other sites More sharing options...
AsankaG Posted January 25, 2023 Author Share Posted January 25, 2023 (edited) 1 hour ago, Radian said: That's quite surprising. I had guessed it was going to be set to 55oC. Is it 10mm pipework back to a manifold for each radiator? Yes, i believe so. Outer Circumference of the white PVC pipe is about 4cm -> 12mm outer diameter both supply and return. And yes supply and return goes via a 6 way split manifold each underneath the boiler (5x radiators total and 1x sealed outlet in the manifolds). To clarify, hotwater side of the boiler is set to 56c. Radiator side is set to 72. I can see the inlet valve bulge (sorry don't know the name of this part 😅) heat up to 67-70c on these radiators when I'm looking at it via a thermal camera. Thanks again for your help Edited January 25, 2023 by AsankaG Link to comment Share on other sites More sharing options...
MJNewton Posted January 25, 2023 Share Posted January 25, 2023 (edited) What’s the temperature of the water reaching the radiators? Edit: Sorry - just seen you said 67-70c! Edited January 25, 2023 by MJNewton Link to comment Share on other sites More sharing options...
Radian Posted January 25, 2023 Share Posted January 25, 2023 65m2 served by 3.5kW in a new-build is a bit troubling. Yes it could be practical if sufficient insulation was used in construction - but it might only be if the as-built performance matches the as-designed. This is rarely the case unless the build was well supervised. Then a number of other factors become relevant. The flow rate established by the circulating pump and the amount of domestic hot water used in the property are two things off the top of my head. But first I think you need a full heat-loss calculation for the property. Is there any documentation to this effect in your handover pack? Link to comment Share on other sites More sharing options...
JohnMo Posted January 25, 2023 Share Posted January 25, 2023 Your EPC should have an energy usage figure on it, that will give you a start Link to comment Share on other sites More sharing options...
Temp Posted January 26, 2023 Share Posted January 26, 2023 When it's struggling to achieve the set temperature does the boiler run continuously or cycle on and off? Link to comment Share on other sites More sharing options...
Conor Posted January 26, 2023 Share Posted January 26, 2023 How quickly do the rooms cool down if the heating is turned off? Link to comment Share on other sites More sharing options...
AsankaG Posted January 26, 2023 Author Share Posted January 26, 2023 Thanks all for your feedback and replies. Hope I can answer all of your questions here. 16 hours ago, Conor said: How quickly do the rooms cool down if the heating is turned off? Checking the last few days, it is about 1c/per hour but tapers off closer to 15c. 20 hours ago, Temp said: When it's struggling to achieve the set temperature does the boiler run continuously or cycle on and off? Boiler is running constantly but I can a pump cycling high/low. 22 hours ago, JohnMo said: Your EPC should have an energy usage figure on it, that will give you a start EPC is rated B and the site say for space heating energy estimate to 406kWh & water heating at 1730kWh per year. 22 hours ago, Radian said: 65m2 served by 3.5kW in a new-build is a bit troubling. Yes it could be practical if sufficient insulation was used in construction - but it might only be if the as-built performance matches the as-designed. This is rarely the case unless the build was well supervised. Then a number of other factors become relevant. The flow rate established by the circulating pump and the amount of domestic hot water used in the property are two things off the top of my head. But first I think you need a full heat-loss calculation for the property. Is there any documentation to this effect in your handover pack? Thanks for the detailed explanation. From your experience what would be the required kW heat this size of a place? This is a mid floor flat if it makes a difference. However, one of the bedrooms has an open storage space underneath it. I've checked my handover pack and it doesn't include any calculation for the heat-loss or any schedules for plumbing/heating. I'm trying to get my hands on this info. Link to comment Share on other sites More sharing options...
Radian Posted January 26, 2023 Share Posted January 26, 2023 10 minutes ago, AsankaG said: From your experience what would be the required kW heat this size of a place? Unfortunately it's almost impossible to say without understanding the exact construction and layout i.e. surface area of external walls and it will also depend on the occupancy levels in adjoining flats. The bedroom with open space below is a particular concern. Is this room noticeably colder than others? Link to comment Share on other sites More sharing options...
RobLe Posted January 26, 2023 Share Posted January 26, 2023 1 hour ago, AsankaG said: 23 hours ago, JohnMo said: EPC is rated B and the site say for space heating energy estimate to 406kWh & water heating at 1730kWh per year. The EPC space heating figure is very low, I’m wondering how to square that up with not managing to heat the place at that flow temperature. Could you take a thermal pic of the rad, but find the hottest part of it - is that pretty much the boiler flow temp? Rads generally have a temp distribution over them. Could you log the gas meter, and read again in 24 hours? Also take a pic of the meter, it hopefully says what the figures mean (kwh/m3/ft3). Are your neighbours, left right up and down heating their flats - You’d notice with your thermal camera? Link to comment Share on other sites More sharing options...
Conor Posted January 27, 2023 Share Posted January 27, 2023 I'm thinking this is a case of a build not matching the claimed specification. 1c loss per hour is a lot for a band B house. Was their an airtightness test done on each unit? Are there any noticeable cold spots on walls, any gaps around windows? How does the insulation in the loft look? 1 Link to comment Share on other sites More sharing options...
ProDave Posted January 27, 2023 Share Posted January 27, 2023 If the water is leaving the boiler at 70C why are the radiators only max 48C? where is the heat being lost? Use the FLIR to trace the water flow from the boiler to the radiators along the pipes to see what is happening. I would expect the water entering the radiators to be hotter than that leaving, but that does not appear to be the case. I suspect inadequate flow rate? turn the pump speed up? Link to comment Share on other sites More sharing options...
Temp Posted January 27, 2023 Share Posted January 27, 2023 Check the flow pipe temperature. Might be set to 72 but is it producing that. Link to comment Share on other sites More sharing options...
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