johny_99

Thanks all! will get someone in to look at rewiring it.

I believe the nest is working as intended, as in it does turn the boiler on to heat the water at the set times. I believe the nest is supposed to act as the time switch you're referring to? Could it be that the cylinder thermostat doesn't know about the nests set on/off times in the morning/afternoon (wired wrong), and is constantly trying to heat the water if it's not up to temp? That would explain why the boiler turns on/off all day/night if the cylinder thermostat is turned up. We only have our boiler set to 60°c, perhaps that's not high enough to heat the cylinder being set above 40°c? Hi Peter Thanks for that. I had expected as much as the installer really didn't seem that competent. Don't suppose you or anyone here knows of a decent guy in the Staffordshire area?

Hi Dave That's interesting. We have the nest controlling our upstairs heating (regular radiators) and our hot water cylinder. The nest is programmed to heat the cylinder for 30 mins twice a day. I had thought this was how it was meant to work as it was the same before the new boiler/tank was installed. I thought the cylinder thermostat was connected to the wiring centre to bypass the nest and turn the boiler off when the water was up to temp. So the cylinder thermostat is meant to keep the water at a constant temperature all day/night? That seems a bit wasteful for us and we would be happy just heating the water a couple times a day.

Hi all I was hoping someone could advise on what might be causing an issue I'm getting with my boiler / hot water cylinder setup. For some reason, turning the thermostat on the hot water cylinder up past 40°c causes the boiler to turn on, and if I leave it above 40°c the boiler turns on/off intermittently. Usually every 10/15 mins the boiler would turn on for 10~ mins and turn off again. If I turn the thermostat down, there's a clicking & whirring noise (coming from the metal box next to the cylinder thermostat) and the boiler turns off, and stays off. Also a clicking noise when I turn the thermostat back up, and then the boiler turns on. We have a nest controlling our how water so it should only turn on for 30 mins in the morning and 30 mins late afternoon. The installer doesn't know what's wrong and insists it's not a fault thermostat. I'm also reluctant to get him back in as I'm not convinced he knew what he was doing as he said it could be a wiring issue but doesn't know. The setup is quite complicated (at least to me as I know nothing about this) as we have a wiring centre with a nest, underflowing heating hub, cylinder thermostat all having cables going into it. I will attach photo's, but I don't know how useful they'll be considering the mess of cables. I was just wondering if anyone had seen this issue before and had any recommendations? Thanks

Thanks all. All good info I will take on board. I will definitely be looking at improving our insulation.

This is our first house of our own and we like it I can't see us leaving anytime soon so I think 10+ years

Thank you all. It appears that the correct decision is a new condensing boiler. Perhaps I can revisit ASHP's when/if the efficiency improves, or LPG becomes ridiculously expensive. Probably over a years supply of gas I also did not know this. Thanks! However, this would require new radiators in every room as this was the temperature I was adviced to run a heat pump at. Are the savings that substantial in condensing mode that it's sensible to upgrade radiators? Thanks!

Thanks so much for that information, JSHarris. I questioned the installer about the high flow temp needed and I was advised the heat pump in question (Nibe f2040-12) "can still maintain a COP of 3.8 at the design external temperature of -2.2" (his words exactly). I did not know about the defrost cycles, thank you! If I understand you correctly, I don't think the hybrid heat pump would be an option. When getting the quote for the heat pump, part of the job was to oversize the radiators in every room (singles to doubles mostly and even adding an additional radiator in one room). The 50 degree flow temp was the required temp after doing this. See, I was also confused about this part (I feel a bit stupid). If I was paying 4.43p per kWh for the pump, and 5.5p for LPG, it's only cheaper if the pump heats the property in around the same time?

Hi I realise this might not be the best forum for this type of question but I'm not sure where to ask it. I'm trying to work out if an ASHP is right for my family and our property. Main points to consider: We're currently using LPG with a 20 year old boiler (75% efficiency I think) Our LPG costs us 38ppl (flogas like changing the price a lot though and this is the cheapest it's been for a while) Electric is costing us 13.3p kWh LPG is costing us 5.5p kWh Required flow temp needed is 50 degrees as it would be used with rads So as I know these variables, to work out the min COP, is it as easy as dividing the electric cost by the lpg cost (2.4~)? But then I need to factor in running times somehow? e.g. if the lpg boiler heats the property sufficiently in 4 hours, due to the ASHP's lower temp it might take 12 hours to heat to the same level Surely I don't just multiply the min COP by 3 as it's going to run for 3 times as long? Thanks!