Jde00 Posted March 7, 2020 Share Posted March 7, 2020 (edited) Hi all I’m purchasing a new build and the developers are installing an ashp central heating system. I have a ton of questions but first let’s describe the house and the system 1) 3 storey 4 bedroom semi town house 2) NIBE F2040 system (unsure as of yet what output they are installing) 3) water tank and control system in first floor. 4) low temperature radiators throughout the house, but no underfloor heating 5) house is a single heating zone 6) thermostat in ground floor, all radiators have TRVs what are your initial thoughts on this installation? i thought I’d ask first, before commenting on my own concerns. disclaimer, I’m not a professional at all, but I’m a scientist and like to understand the engineering aspects of these systems. cheers. Edited March 7, 2020 by Jde00 Link to comment Share on other sites More sharing options...
ProDave Posted March 7, 2020 Share Posted March 7, 2020 If it's a developer house then you can almost guarantee the most important thing, the insulation levels and air tightness will not be as good as they could be, so right from the start you have that disadvantage. That would be where I would direct my questions. 1 Link to comment Share on other sites More sharing options...
Mike Posted March 7, 2020 Share Posted March 7, 2020 Agree with ProDave, particularly about finding out what level of airtightness they can guarantee you. Also, might be worth looking at the possibility of fitting a MVHR system, if they're not too far advanced. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted March 7, 2020 Share Posted March 7, 2020 You want to get a good COP so you probably need to do a few sums based on your expected SAP figures and then check out the ASHP unit to be sure they are a close match, too small and it will struggle and be noisy, too big and it will be noisy and large! Are you getting the RHI? Link to comment Share on other sites More sharing options...
Ferdinand Posted March 7, 2020 Share Posted March 7, 2020 (edited) Welcome. As hinted at, you need to understand the spec, and the backround, and also your requirements (if they will only do a little extra you need to know what that should be for your maximum benefit.) If it is Building Regs only, then it may not be appropriate to have a single heating zone - it depends what the overall energy demand is going to be and whether you are comfortable with that, however you could workaround that using Thermal Radiator Valves to control each room to an extent, or using so called "Smart TRVs" to give you a measure of centralised control. I think @pocster has those in his HMOs. It is about understanding what you are getting, and evaluating that against what you think the house requires - then using that info to demand any necessary changes or choosing options as early as possible. Ferdinand Edited March 7, 2020 by Ferdinand Link to comment Share on other sites More sharing options...
Pocster Posted March 7, 2020 Share Posted March 7, 2020 3 minutes ago, Ferdinand said: Welcome. As hinted at, you need to understand the spec, and the backround, and also your requirements (if they will only do a little extra you need to know what that should be for your maximum benefit.) If it is Building Regs only, then it may not be appropriate to have a single heating zone - it depends what the overall energy demand is going to be and whether you are comfortable with that, however you could workaround that using Thermal Radiator Valves to control each room to an extent, or using so called "Smart TRVs" to give you a measure of centralised control. I think @pocster has those in his HMOs. It is about understanding what you are getting, and evaluating that against what you think the house requires - then using that info to demand any necessary changes or choosing options as early as possible. Ferdinand Yes ! I have genius hub installed in 3 HMO’s works well . Battery failure being the most annoying thing and thick tenants not understanding it ... Link to comment Share on other sites More sharing options...
Jde00 Posted July 2, 2020 Author Share Posted July 2, 2020 So. Fast forward to July and have finally purchased the house. the insulation and air tightness seems excellent. But I’m still waiting for confirmation from inspection I’m having all sorts of issues with the ASHP. In normal operation the heat pump seems to be cycling as follows: 3 minutes off 2 minutes on. All the freaking time. is this normal operation? the house is empty and it seems it has used close to 30 kWh in just over 4 days. With just the fridge, and the BT router on. is this pump a dud or has thrrrr been a serious problem with the installation??? Link to comment Share on other sites More sharing options...
ProDave Posted July 2, 2020 Share Posted July 2, 2020 I assume there is no heating on at the moment? Remind us which ASHP you have (if it has been mentioned already) Our house uses about 8kWh per day to power "stuff" where "stuff" covers everything except heating and hot water. One day I will measure each individual appliance to see which use what. electricity used to power "stuff" is about twice what we use for heating and hot water. At this time of year my ASHP is using 0kWh per week for heating, and typically 15kWh per week for DHW, less when it is sunny as surplus solar PV is diverted to the hot water tank so on a really sunny day no ASHP input required. So typically at the moment the ASHP will come on at it's set DHW time and run for no more than half an hour continuously until the DHW tank is up to temperature then stop and remain stopped until a significant amount of hot water has been drawn off. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 2, 2020 Share Posted July 2, 2020 2 hours ago, Jde00 said: is this normal operation? the house is empty and it seems it has used close to 30 kWh in just over 4 days. With just the fridge, and the BT router on. A fridge could use that much if it is constantly running. A router will just draw a few watts. You say it is constantly cycling this sounds like it has not been set up at all, or is faulty. Turn it off and get the plumber back in. Link to comment Share on other sites More sharing options...
SuperJohnG Posted July 2, 2020 Share Posted July 2, 2020 Its sounds like its short cycling, have a search on the forum for that phrase and you should find some possible reasons . Link to comment Share on other sites More sharing options...
Jde00 Posted July 3, 2020 Author Share Posted July 3, 2020 Thanks. The plumbers are coming in. in just a few weeks since installation the pump has had close to 18,000 cycles, I assume every 3 minutes. ive turned it off for now as it was also giving out high pressure alarms a couple of times a day. yeetrrday it went haywire while checking hot water in the kitchen. Running hot water for a 3 minutes caused the radiators to heat up!!! And then the ASHP controller switched to heating. Even through the climate temp was set to 10°C! i think someone seriously messed up the installation ! Link to comment Share on other sites More sharing options...
ProDave Posted July 3, 2020 Share Posted July 3, 2020 It sounds like it is seriously messed up. Why am I not surprised? The 3 minutes on 2 minutes off sounds awfully like the HP thinks it should be heating the radiators, but something else (like a motorised valve on the heating circuit) is closed so all the HP is doing is heating and re heating a short run of water running round a few pipes. It should not be your problem to sort out, the developer should sort it. If the heating is off (or is above the target temperature) then the HP should not do anything until hot water is needed. Have you got an immersion heater you can use for hot water until it is fixed? 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted July 3, 2020 Share Posted July 3, 2020 (edited) 1 hour ago, Jde00 said: 18,000 cycles That is 50 cycles a day if spread over a year. I would expect no more than 12. So the HP may already have done 4 years work, and in terms of wear more as generally the 'damage' is done during the start up. Edited July 3, 2020 by SteamyTea Link to comment Share on other sites More sharing options...
SuperJohnG Posted July 3, 2020 Share Posted July 3, 2020 One downside here is that it is likely beyond most plumbers to set it up, in terms of them being interested in doing it or having the appropriate training on a building site to complete the task. A specialist plumber or interested person would have more luck. Link to comment Share on other sites More sharing options...
Jde00 Posted July 6, 2020 Author Share Posted July 6, 2020 Apparently one of the pipes was clogged with antifreezer. We now have hot water but on the unit is still short cycling to 2.5 minutes every 5 minutes. Definitely not energy efficient not to mention excessive wear and tear. Link to comment Share on other sites More sharing options...
ProDave Posted July 6, 2020 Share Posted July 6, 2020 Post some pictures of the controls, piping, hot water cylinder etc. Then do some basic checks and (with reference to the pictures) tell us what pipes are hot and which are not. Also include pipework and controls relating the the heating side of things which at the moment should all be cold. If there are any thermostats or thermometers on the cylinder for instance tell is what they are set to or what they are reading. I fail to see how antifreeze can "clog" a pipe. It is a liquid. Even when poured in neat it will soon mix with the water to give a dilute mixture. I suspect this was a BS excuse for "I have not got a clue, I messed about without knowing what I was doing and I think it is now working" Link to comment Share on other sites More sharing options...
Jde00 Posted July 6, 2020 Author Share Posted July 6, 2020 (edited) 53 minutes ago, ProDave said: Post some pictures of the controls, piping, hot water cylinder etc. Then do some basic checks and (with reference to the pictures) tell us what pipes are hot and which are not. Also include pipework and controls relating the the heating side of things which at the moment should all be cold. If there are any thermostats or thermometers on the cylinder for instance tell is what they are set to or what they are reading. I fail to see how antifreeze can "clog" a pipe. It is a liquid. Even when poured in neat it will soon mix with the water to give a dilute mixture. I suspect this was a BS excuse for "I have not got a clue, I messed about without knowing what I was doing and I think it is now working" Probably!! What concerns me is the number of cycles as mentioned above and the electricity use. The manufacturer NIBE is coming at some point so if there is a mess they should be able to find it and say so. another thing the plumber insisted was to turn the immersion heater on. Obviously if there's a fault with the actual compressor, the immersion heater is only going to hide it by using a ton of electricity to heat the water instead of using the heat pump. Edited July 6, 2020 by Jde00 Link to comment Share on other sites More sharing options...
ProDave Posted July 6, 2020 Share Posted July 6, 2020 Well yes you should turn the immersion heater off and give the HP a chance. But as I said before, it should not run all the time. It should run long enough to heat the tank then shut off completely until you have used some hot water. If as you suggest it is running continuously all the time, then it says to me it's either got an impossibly high target temperature set that it can never reach, or it is circulating water around the heating loop even though the heating should be off. Link to comment Share on other sites More sharing options...
Jde00 Posted July 8, 2020 Author Share Posted July 8, 2020 We'll see, the NIBE installers are next door but from what I can see, the other ASHP is doing the same 3 minutes on 5 minutes off. That's 22.5 minutes of every hour that the compressor is running. In Summer............. Link to comment Share on other sites More sharing options...
Jde00 Posted July 10, 2020 Author Share Posted July 10, 2020 Seems like the heat pump issues were sorted. There were a whole bunch of things not properly installed. Hot water works as expected, only one or two cycles per day to top up the tank. However it seems the external heat medium pump is running almost continuously (with compressor off) and the climate set to 18 degrees (indoors temp 22, outdoors 14). Is this normal behaviour for these systems or have they messed up with something else by fixing the compressor? lol thanks! Link to comment Share on other sites More sharing options...
joe90 Posted July 10, 2020 Share Posted July 10, 2020 1 hour ago, Jde00 said: external heat medium pump is running almost continuously (with compressor off) I may be thick but I don’t understand this, the compressor is part of the ASHP and when heat is called for it starts running. At other times it should not run. If the ASHP is running something is calling fir heat, DHW or radiators/UFH. If the hot water tank is full of hot water and your stat is below room temp it should not be running! When it’s running can you tell if it’s heating DHW or heating? (Hand on pipes to tell which is warm/hot?. Link to comment Share on other sites More sharing options...
Jde00 Posted July 10, 2020 Author Share Posted July 10, 2020 (edited) I don't understand it either ! Compressor isn't running. Heating is set to 18degrees (also tried 5 earlier) and radiators are cold. The compressor kicked in this mornign for hot water but I noticed a while ago that after stopping, the nibe controller still showed only 1 out of 3 marks for hot water (the 3 step level next to the water drop). I can hear water in two pipes coming out of one of the small buffer tanks, but didn't check whether they were hot or not. I'll check later. For now what I'm trying is to activate lux mode for hot water to see if the 3 levels get full. then stop and see whether hot water is lost without anyone actually using hotwater. Edited July 10, 2020 by Jde00 Link to comment Share on other sites More sharing options...
joe90 Posted July 10, 2020 Share Posted July 10, 2020 6 minutes ago, Jde00 said: The compressor kicked in this mornign for hot water but I noticed a while ago that after stopping, the nibe controller still showed only 1 out of 3 marks for hot water (the 3 step level next to the water drop). I am not conversant with your controller (mine was a nightmare and I still don’t understand it, but it works!). Is your hot water hot enough? Do you know what temp the DHW is set too? Is the DHW tank hot most of the way down?. Just in case you don’t know this, an ASHP delivers warm water slowly unlike a gas or oil boiler so it will take much longer to heat your DHW tank. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 10, 2020 Share Posted July 10, 2020 1 hour ago, Jde00 said: However it seems the external heat medium pump is running almost continuously Do you mean the circulation pump for the UFH\radiators or the one that pumps fluid within the actual ASHP (depends on design). While not desirable to have the circulation pump on all the time, it does even out the room temperatures. Link to comment Share on other sites More sharing options...
joe90 Posted July 10, 2020 Share Posted July 10, 2020 It may be that the ASHP is off but the circulation pump still runs for a while till temp even out (like an electric fan on a car after a long run). Link to comment Share on other sites More sharing options...
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