RogerH

Thanks everyone. I will act on the advice given and report back in the future.

Thanks James, I will start to use weather compensation. The rads were enlarged to suit the heat loss survey carried out by installers. We found that the living room was not getting warm as quickly as the other rooms and I read some stuff somewhere about the importance of volume of water, and because we have no buffer we doubled the rad size in living room. So far perhaps slightly better COP but it only happened 2 weeks ago. No I don’t know how to estimate water volume in system and then use that info. No room for buffer tank in house so I’d have to build a box for it outside if it came to that. I do wonder whether it is a good idea to invest in some more accurate way of determining what is happening. Not sure I am geeky enough to get into open monitoring and more cost though. The other issue that has been noticed by the NAPIT technician who came to the house is that there are a lot of 90 degree bends between the ASHP and the rads. All the pipework is squeezed into an under stairs cupboard. I really don’t know how significant this sort of thing is.

We only have one zone. What do you mean by ‘get rid’?

Sorry,typo. All rads have TRVs and they are all open. We don’t use them.

Not using TRvs except that they. Are always open . Smallest circuit?

Sorry that this has become a rabbit hole. I didn’t know how much help to expect from the forum. Thanks for all you replies. est heat demand Pa from heat loss survey:7356 (actual delivered energy from heat pump (2022) 3744), pleased but not sure why there is such a difference area of house: 100m2 model: PUZ-WM60VAA no buffer straight to radiators 1 room thermostat in living room supplied by Mitsubishi in heating season we set back temp on stat to 18 degrees and then to 19.5 daytime flow temp 38 degrees (didn’t spend much time using adaptive mode) not tried wether comp yet

JamesPa I don’t really understand. I suppose what concerns me about connecting cylinder to heat pump is the cost of paying someone to do it, and who would do it, then complicating a system, that we understand. I need to know that the change would yield a good result. At the most we could save about 260 kWh pa. Because I don’t have the technical skill or knowledge I would be relying on someone else and trusting them. So far the installer(s) used have not been that knowledgeable or trustworthy. The solar panels ,house batteries, solar diverter and car charger have worked out fine after many workings out with technicians over the phone. The heat pump not so much. With that I feel we are trying to make the best of an oversized pump for at least seven years because financially we are tied to it it with the RHI payments. After that we will think again. in general it seems that there are no whole house retrofit experts (near us anyway) who know how all the bits work together and thus exactly what the best options are. The heat pump engineer who installed the mixergy tank did not understand the solar diverter so wouldn’t connect it up. The solar installer (initially) couldn’t design the system to work with the solar diverter and car charger, and seemed reluctant to talk to the company who installed the car charger. No one seemed to be able to work out easily where to put the ct clamps, for example. The heat pump installer was utterly unresponsive about anything until NAPIT got on his back. No one seemed to be able understand the work I’d done already, for example that we had so much insulation that we really don’t need radiators upstairs or that our max heat loss at minus 3 really is under 3kW and therefore a 6kw heat pump won’t be able moderate low enough and thus we are left with cycling and thus a COP of 2.4. All this stuff we have had to learn ourselves. as far as MELCloud goes I will contact Mitsubishi.

Thanks again. Will give some thought to using the heat pump for DHW . We used 382 kWh of grid energy for hot water in 2022. Most is heated by solar. So presumably we could reduce that to about 130 kWh if we connected the heat pump. I will give it some thought, the tank is ‘heat pump ready’. Financially it is cheap because we only use octopus Go (overnight) at 7.5p kWh.

Thanks again. Steamy tea, the DHW is from PV solar diverter (eddi), octopus go overnight , and a mixergy tank (very efficient). PhilT, the mel cloud app is utterly inaccurate when I ask for an energy report. It is saying delivered energy is about half of what the ftc says and has the COP graph wildly wrong. So either turn if off in summer or put it on a weekly cycle ? ST, does that mean switch it on for a few hours once a week over summer? As far as base load goes, we don’t mess with the fridge, router, car charger, hot water but all else that plugs into sockets is switched off when not in use using smart plugs. I have quickly gone through the other thread on standby of ecodan and it seems that about 25w is what it uses (but not in the heating season). 20 kWh per summer month may not be too far off as a guess. I strongly agree that installers should be upfront with this sort of thing.

Thanks people, will check out the tread you suggested ST. 20w is 20w . We turn off our MVHR in summer and it only uses 9w. so is it safe to turn it off?

Hi All, this is my first post. We have a 6kw ecodan installed to radiators in dec 2021. We have hot water taken care of with a mixergy tank and solar PV and octopus go so not connected to heat pump. Therefore we have no need for it over summer. It looks like the pump uses about 20 kWh of energy over each of the summer months. I only noticed when I was looking back at the ‘consumed’ monthly figures in the ftc. In summer there are consumed figures but nothing ‘delivered’ . Our total kwh consumed by pump for 2022 was 1560 kwh so quite a bit of that, about 120 kWh was from it ‘doing its own thing’ in the summer. Can I safely turn it completely off in summer? Also I have been taking daily readings from ftc recently (of delivered and consumed energy), how accurate do people think these figures are for the purposes of determining COP? ( Also the Mitsubishi app is hopeless). If the consumed kwh for summer have not delivered anything then they have to be deducted from the total delivered figure to get an accurate COP. Also if I want to really get on top of our COP is it worth doing something like open energy monitoring? By the way our COP for 2022 was 2.4 so I am working on ways to improve it., also the installer has gone bankrupt! BTW we have been through all the NAPIT complaints procedure to no avail. They think the pump was installed properly. In general, the installer was hopeless and now non existent , MELCloud hopeless, NAPIT hopeless. But we did get RHI and we don’t use much energy because we have done a deep retrofit (37 kwh per m2 for space heating), not because the pump is working efficiently. And relax.