Onoff Posted February 5, 2019 Share Posted February 5, 2019 10 minutes ago, AliG said: Don't forget we are trying to help @Jude1234 get the heating bill down. To summarise my earlier post, the biggest difference will probably be sealing up all the air leaks, unless some idiot has forgotten to insulate your loft. How to go about pinpointing said leaks then? Link to comment Share on other sites More sharing options...
Ferdinand Posted February 5, 2019 Share Posted February 5, 2019 2 minutes ago, Onoff said: How to go about pinpointing said leaks then? I think we have done that before. In this weather one way is to heat it up and take a lot of thermal images. The outgoing air drafts may well show. Link to comment Share on other sites More sharing options...
Ed Davies Posted February 5, 2019 Share Posted February 5, 2019 If a thermal imager isn't to hand an infra-red thermometer can help a lot. Just takes a bit longer to scan around looking for cold spots. Link to comment Share on other sites More sharing options...
AliG Posted February 5, 2019 Share Posted February 5, 2019 (edited) When it is cold outside running your hand along spots where there may be leaks. Also take your socks and shoes off and feel for cold spots with your feet. I see people using smoke when they do blower tests, but frankly I suspect that at 4.5 ACH there should be plenty of leaks that you can just feel. After that thermal imaging of the outside of the house when the heating is on will show if there are leaks and also if there are problems with the insulation. You can get a Flir One Gen 3 for £200 odd and then sell it on Ebay when done with it. Edited February 5, 2019 by AliG Link to comment Share on other sites More sharing options...
Onoff Posted February 5, 2019 Share Posted February 5, 2019 Can you end up with the unfortunate scenario of an airtight dot and dabbed pb layer that is massively cold behind because of lack of parging of the block work the boards are stuck to? Thus you can get a reasonable air test. Link to comment Share on other sites More sharing options...
Declan52 Posted February 5, 2019 Share Posted February 5, 2019 A lit candle and walk round each room and go by every socket, light fitting, corner, window revel etc. Link to comment Share on other sites More sharing options...
newhome Posted February 5, 2019 Share Posted February 5, 2019 Would the air tightness test report not state where there could be areas to improve or do you have to be on site and ask questions? Link to comment Share on other sites More sharing options...
AliG Posted February 5, 2019 Share Posted February 5, 2019 That's a good question. I guess they don't unless someone goes around checking. So the builder just does the test and fills in a box. Job done, house leaks like a collander! 2 Link to comment Share on other sites More sharing options...
Ed Davies Posted February 5, 2019 Share Posted February 5, 2019 1 hour ago, Onoff said: Can you end up with the unfortunate scenario of an airtight dot and dabbed pb layer that is massively cold behind because of lack of parging of the block work the boards are stuck to? Thus you can get a reasonable air test. Absolutely. What Tony on GBF christened a plasterboard tent, where all the insulation is bypassed. One of the many reasons why airtightness tests are to be taken with a pinch of salt. We've had this discussion before but basically the airtighness layer really needs to be much further out in the insulation. My working hypothesis is that a lot of the disappointment with insulation in new builds over the last few years is because of air getting past the insulation layers due to slapdash installation. I haven't seen a convincing contradiction yet. Link to comment Share on other sites More sharing options...
Jude1234 Posted February 5, 2019 Author Share Posted February 5, 2019 1 hour ago, AliG said: Don't forget we are trying to help @Jude1234 get the heating bill down. To summarise my earlier post, the biggest difference will probably be sealing up all the air leaks, unless some idiot has forgotten to insulate your loft. I don't mind the thread going off on tangents if it helps other folks. I am pursuing my builder for the design SAP report and then the EPC. Also they are getting someone in to look at the ASHP to see if that is working properly. Will also pursue the poor airtightness test (in reality it was actually 5.25 I found out today☹️) until we get teh bottom of it. Luckily the builder still has not invoiced his last bill so is now keen to get everything resolved so I will pay! Link to comment Share on other sites More sharing options...
Onoff Posted February 5, 2019 Share Posted February 5, 2019 1 minute ago, Ed Davies said: Absolutely. What Tony on GBF christened a plasterboard tent, where all the insulation is bypassed. One of the many reasons why airtightness tests are to be taken with a pinch of salt. We've had this discussion before but basically the airtighness layer really needs to be much further out in the insulation. My working hypothesis is that a lot of the disappointment with insulation in new builds over the last few years is because of air getting past the insulation layers due to slapdash installation. I haven't seen a convincing contradiction yet. We've seen some member's pi$$ poor builders attempts at sealing around windows and lack of cavity closers! Link to comment Share on other sites More sharing options...
Declan52 Posted February 5, 2019 Share Posted February 5, 2019 9 minutes ago, Jude1234 said: I don't mind the thread going off on tangents if it helps other folks. I am pursuing my builder for the design SAP report and then the EPC. Also they are getting someone in to look at the ASHP to see if that is working properly. Will also pursue the poor airtightness test (in reality it was actually 5.25 I found out today☹️) until we get teh bottom of it. Luckily the builder still has not invoiced his last bill so is now keen to get everything resolved so I will pay! Well I wouldn't be writing any more cheques out until you figured out why you scored such a poor result in the air test and depending on the as built SAP score why your house is cold. Both will be linked but you need it in black and white to prove it. Link to comment Share on other sites More sharing options...
AliG Posted February 5, 2019 Share Posted February 5, 2019 10 minutes ago, Jude1234 said: I don't mind the thread going off on tangents if it helps other folks. I am pursuing my builder for the design SAP report and then the EPC. Also they are getting someone in to look at the ASHP to see if that is working properly. Will also pursue the poor airtightness test (in reality it was actually 5.25 I found out today☹️) until we get teh bottom of it. Luckily the builder still has not invoiced his last bill so is now keen to get everything resolved so I will pay! Was the blower test done with the MVHR running? There was another thread about that. At 5.25 you could probably just turn the MVHR off and would be ventilated by draughts. Do you have a fire or stove that is not sealed with a twin wall flue? That would be another source of a leak. Another thing I found in old houses was take off the plinths on the kitchen and look for holes, also under the sink. As no one can see it they just hack holes in the walls for pipes and cables and don't fill them in. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted February 5, 2019 Share Posted February 5, 2019 The blower test must be performed with the external ducts for the MVHR closed off and sealed. Failure to do this will result in an incorrect set of measurements, that will be pretty massively in error. The blower fan will pressurise and depressurise the house to 50 Pa, which is a heck of a lot higher pressure than the fans in the MVHR could produce, so they would just be overwhelmed and both external MVHR ducts would leak air in or out dependent on the blower fan direction. Link to comment Share on other sites More sharing options...
ProDave Posted February 5, 2019 Share Posted February 5, 2019 35 minutes ago, Jude1234 said: I don't mind the thread going off on tangents if it helps other folks. I am pursuing my builder for the design SAP report and then the EPC. Also they are getting someone in to look at the ASHP to see if that is working properly. Will also pursue the poor airtightness test (in reality it was actually 5.25 I found out today☹️) until we get teh bottom of it. Luckily the builder still has not invoiced his last bill so is now keen to get everything resolved so I will pay! Can you give us any other information about the building? How was it built? masonry or timber frame? did you see it during construction? do you have any photographs? Architects drawings? etc etc. Link to comment Share on other sites More sharing options...
Cpd Posted February 5, 2019 Share Posted February 5, 2019 36 minutes ago, Jude1234 said: Luckily the builder still has not invoiced his last bill so is now keen to get everything resolved so I will pay! Hold on hard to this until your 110% clear that everything is done to the spec you paid for. Link to comment Share on other sites More sharing options...
scottishjohn Posted February 5, 2019 Share Posted February 5, 2019 1 hour ago, AliG said: Was the blower test done with the MVHR running? There was another thread about that. At 5.25 you could probably just turn the MVHR off and would be ventilated by draughts. Do you have a fire or stove that is not sealed with a twin wall flue? That would be another source of a leak. Another thing I found in old houses was take off the plinths on the kitchen and look for holes, also under the sink. As no one can see it they just hack holes in the walls for pipes and cables and don't fill them in. walking round with a joss stick or small smoker -like for a bee hive might show you things if leaks are bad Link to comment Share on other sites More sharing options...
Ed Davies Posted February 5, 2019 Share Posted February 5, 2019 1 hour ago, Onoff said: We've seen some member's pi$$ poor builders attempts at sealing around windows and lack of cavity closers! The classic is sheets of foam insulation in a cavity just floating around lose, with no sealing at all. Sort of thing a thermal imaging camera might help with if it's @Jude1234 's problem. Link to comment Share on other sites More sharing options...
AliG Posted February 5, 2019 Share Posted February 5, 2019 (edited) I went back and checked my calculations from earlier and noticed that I had multiplied by the COP twice. Errors like that creep in when I sneak in an answer whilst working. OK - 1300kWh per month. You have to remember that you don't have any gas. I don't know the exact circumstances in your house so will be guessing a little. I am also using a COP of 3.5 for the ASHP. According to the manufacturers specs, the COP is anywhere between 3 at 2C outside heating water to 55C and 4.7 at 7C outside heating water to 55C. If you only heat water to 35C the COP rises, but I do not know where it is set. Spec below http://www.mastertherm.eu/wp-content/uploads/2019/01/BAxxI.pdf Electricity for lights, cooking etc. Assuming that the average family uses around £500 of electricity a year for these, that is around 300kWh per month(at 14p per kWh). Maybe slightly more in the winter. Adding in UFH pumps and MVHR, this may rise to 400kWh per month. Hot water, apparently the average household uses about 120l per day. Assuming a 50C temperature increase, this would require 7kWh per day. Allowing for heat losses, let's call it 15kWh per day, allowing for a COP of 3.5, this is 130kWh per month at the heat pump. So very roughly 500kWh of your demand is for general electricity and hot water at a COP of 3.5. Thus you are using 800kWh at the ASHP to heat the house. At a COP of 3.5 this is around 2800kWh of heat demand. As I mentioned earlier, I use around 250kWh of gas a day for heating excluding hot water. You are using around 90kWh per day. My house is well but not super insulated and I am still working on closing up all the leaks. You are using around 1.6x as much energy per square metre for heating. Not great but not disastrous. However my house is not cold when I use this much energy. There are really two problems - Are you using too much energy and why is it cold and they are interlinked. I have looked at the heat pump specs, but maybe someone who knows them better could look. 9kW is the output, it seems it would use around 3.5kW of electricity at this level, which is not the same as the COP, but I may be misreading the spec. You are using around 27kWh a day for heating, this suggests that the ASHP is running around 7-8 hours a day for heating. It should be able to put out more than enough energy to heat your house in almost any circumstance, although this would mean running it longer and using more energy. You mentioned earlier that you are home 6.30-8 and 5-10.30. Is this when you are running the heating/ASHP? UFH has slow heat up times. Depending on your flow temperature, thickness of your slab etc you might need the heating to come on 1-3 hours before you want it to be warm. Some UFH thermostats like Heatmiser try to allow for this, but otherwise you have to figure it out yourself. I would expect you to have to set the heating to be on at 5am to be warm at 630am and then again at 3.30ish in the afternoon. Does the house feel cold when you come home, but warm up by 7pm? The advice to run the heating 24hours a day is not quite right, normally what you do is set it back 2 or 3 degrees when not using it and set the heating times earlier than when you actually want it to be warm. Roughly in your case I would set it to 21C from 5-7am and again from 3.30-9pm then 18C the rest of the time. Indeed the COP of your heat pump is much better when the water is less hot, so it may be better to run the heating for longer periods with a lower flow temperature. But this won't work at the moment as your heat losses are too high. I suspect that your pump is not running long enough and driving a high enough flow temperature in the UFH to warm up your house. You can certainly make it warmer and warmer at the right times, but this might drive your electricity bill up by another third. And so where using too much energy and it being cold become interlinked is the air leakage or insulation problems. 9kW should be more than enough energy to heat your house and keep it cosy. But if you have a lot of draughts then there will be periods where the house leaks heat faster than you can heat it up. In extremis the house could lose heat faster than you can actually get it out of the slab and it will be cold.. You can compensate by running the UFH longer and with a higher flow temperature but will use more electricity to do so. You need to reduce the house's heating requirements to what is expected. My guess is that if you fix any obvious leaks and insulation problems you can keep the house warm using the current amount of electricity, but maybe not use less electricity. You are going to use around 4-5000 kWh per year for heating, this is the peak now and 6000 kWh for everything else. Around £1500 a year for all energy use wouldn't be a bad figure if it was actually comfortable in your house. Edited February 5, 2019 by AliG 3 Link to comment Share on other sites More sharing options...
Cpd Posted February 5, 2019 Share Posted February 5, 2019 Great summary. Link to comment Share on other sites More sharing options...
PaulH Posted February 7, 2019 Share Posted February 7, 2019 (edited) I'm off. Edited February 7, 2019 by PaulH Link to comment Share on other sites More sharing options...
ProDave Posted February 7, 2019 Share Posted February 7, 2019 They can respond to timers. I have mine set up with a conventional 3 channel central heating programmer, for upstairs UFH, downstairs UFH and hot water, all independantly controllable from the time clock. I have heating to come on early in the morning and off a 9PM Hot water does not come on until slightly later and goes off at 10PM. I did this because the controller that came with it although it can do timer functions it was devilishly complicated to set and does not have the usual advance, 1 hour boost etc functions of a normal programmer. It did take some ingenuity to get the hot water controlled by an external time clock though. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted February 7, 2019 Share Posted February 7, 2019 1 hour ago, PaulH said: ASHP's are not gas boilers - they do not respond to timers - ie 3 hr's in a morning and 5 hrs on an evening. they don't respond quick enough due to the low temperature output. I turn mine on in October and off in April - running costs vastly reduced, whole house a comfortable, constant weather compensated temperature. Undersizing as well as oversizing cause issues - there is no guess work involved in sizing a heat pump - it's a specialist area - DIY can work but it's usually 'luck' that gets it to work satisfactorily. All I can say is that I've been running ours on a timer so that it only comes on during the E7 period to "charge" our passive slab with heat overnight (much like a storage heater) and it works extremely well, even in the recent very cold spell. Having the ASHP only running on either E7 during the winter, or from excess PV generation when in cooling mode in very hot weather, significantly reduces the running cost (just about halves it). As for sizing the heat pump I didn't find that at all challenging. I had the heating requirement for the house from thermal modelling, so knew the worst-case heating power needed in worst-case weather, and it was pretty simple to just match that to a range of heat pump performance figures in order to get the sizing right. As it turned out, it wasn't very critical, and any of the smaller (4 kW to 8 kW) units would have met our requirement easily. What I have found is that the factory settings that were programmed into our re-badged Carrier ASHP were way off being optimised for the climate in the South of the UK. The "manufacturer" (who just re-badged a heat pump from the OEM) turned out not to understand how some of the settings impacted on performance in cool, damp, weather (which I found by experiment to be the least efficient operating region). I ended up going back to first principles to determine what the settings should be, and have had an installation that consistently runs with a COP of between 3.5 and 4 all year around (including when used for summer cooling). I've also found that weather compensation just doesn't work at all well, and just tended to reduce COP and increase the frequency of defrost cycling. Having now had the ASHP running with a flat flow temp vs. outside temp curve for more than three years, and having improved the overall mean COP by around 0.3 by doing so, I know beyond doubt that changing the flow temperature with outside air temperature actually decreases efficiency and increases running cost. I should add that weather compensation had no impact at all on the heating performance; that remained the same whatever curve was tried (not surprising given that the flow is mixed down to about 26°C at the UFH manifold). Link to comment Share on other sites More sharing options...
ProDave Posted February 7, 2019 Share Posted February 7, 2019 Just to add to the above post, I turned off the weather compensation as well. Mine just runs with one set low temperature when doing under floor heating, and a different set higher temperature when doing hot water (they usually never do both at the same time) Link to comment Share on other sites More sharing options...
Onoff Posted February 7, 2019 Share Posted February 7, 2019 On 05/02/2019 at 09:46, Onoff said: That when I retire my annual oil bill will probably eclipse my pi$$ poor pension makes me wish I lived in a passive spec house. You only pay for insulation ONCE. You are at the mercy of A N other whatever energy source you consume. What he said: Link to comment Share on other sites More sharing options...
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