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Kevm's Achievements


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  1. Back to the original subject. That was 24W when running, but in stop mode. I'm on holiday now and the system is on standby. Not a full power down but standby on the control panel. Over the last 5 days Melcloud is reporting 2.9kWh used in total. I make that 24W again so very consistent. I don't think that's anything to be concerned about. 24W isn't any sort of heater or pump, just the FTC6 ticking over in standby.
  2. You might be right; I don't have any data (yet) for long periods of off time. My longest 'stop' samples are from my overnight 5 hour downtime.
  3. It's very close to 25W no matter what period I choose.
  4. My 14kW monobloc Ecodan with MMSP records minute by minute data. When it's in 'stop' mode it averages a bit under 0.4 Wh per minute. I know from the way it's wired up that that's all the power being used by everything. About 25W I think?
  5. No,that's not true. The COP has nothing directly to do with insulation or draughts. A poorly insulated/draughty house has a higher heat demand. If you meet the heat demand with a suitably sized heat pump and emitters with a reasonable flow temp your COP will be good. If you undersize your heat pump and/or require high flow temps it won't be. These last two sentences apply whether you're heating a passivhaus or the Albert Hall. Of course a good COP isn't everything and the more you can reduce demand the better. There are plenty of houses with solid walls running heat pumps successfully.
  6. To expand on my slightly unhelpful response, I've also called Mitsubishi Technical a couple of times with questions and they have always been very helpful. Their documentation is good and easily available. I have an outside monobloc unit, a non-Mitsubishi cylinder and the FTC6 controller. The FTC6 controls everything, including the outside unit, cylinder, immersion, external pumps and diverter valves.
  7. My Ecodan has been faultless and very efficient after a year's use. I haven't posted a review on Trustpilot.
  8. Not sure if have this but it's a link to lots of Grant/Chofu manuals and other info. https://github.com/aerona-chofu-ashp/docs Mitsubishi allows multi-point curves and also has a room temperature more that claims to use a combination of outside and room temps. I haven't tried it though.
  9. Just be careful what you think is a 16kWh ASHP. Some manufacturers can only achieve their rated output under very benign conditions I know Midea is one, there may be others. Mitsubishi can achieve theirs (and more) in most conditions; there will be others like this too.
  10. Phone them when they are open. They tell you their opening hours in a recorded message if you phone when they are closed. In my experience, when they are open, they answer the phone and are helpful.
  11. It's not me; I just C&P from another forum. The guy in question was going for RHI so he would have had a full heat loss calculation done
  12. I would be uneasy too. Any ASHP system designer/installer should do a proper heat loss calculation. It will be routine for them. And your house is a new build, right? My 1990 bungalow has a heat loss of about 56 w/m2; I would have thought yours would be much lower. You need the proper calculations.
  13. Here is some info about Grant ASHPs from a user on another forum. I've just cut and pasted it so no guarantees... I was in exactly the same situation 3 months ago - lead times on the Ecodan cylinders were out to 12 weeks and we couldn't wait. So we went with the Grant 13kW. House is about half the size of yours, radiators, TRVs, oil boiler, Cambridgeshire. The installer recommended the 10kW Grant but I went for the 13kW as it's double fan and supposedly quieter (and the actual spec sheet says they are respectively 10.5kW and 11.4kW at 55C, which is more realistic since we have radiators - so the 13kW isn't actually massively more powerful, although the flow rates are higher). It remains to be seen how it copes in spring and autumn when only a little heat is required, but in winter it seems to be coping fine. Now, the Grant heat pump seems to be a good unit. It's made in Japan by a company called Chofu Seisakusho Co. Ltd - Grant buy them from a European distributor and rebrand them. From what I've seen of the unit and the documentation it seems to be good build quality. I've been curating some documentation here - the Chofu installation manual, service manual, etc and marketing information from other countries. The problem is that Grant is really an oil boiler company, and they want a heat pump to behave like a boiler, which it isn't. My install is absolutely by the Grant book, the problem is that Grant took the perfectly good English installation instructions from Chofu, deleted lots of stuff (it should do cooling, which they don't admit to. I enabled the cooling button, but can't really test it in winter), and added a relay box to interface it to UK on/off boiler controls. The trouble is that on/off thermostats aren't good for heat pumps - my installer provided a Honeywell Lyric controller which does TPI. TPI is a way that, by default, it looks at every 10 minute period and decides how much the boiler should be on. Result is that it turns the boiler on for say 3 minutes, then off for 7 minutes, repeatedly throughout the day. You can set that back to 20 minutes, but can't turn off TPI. This is terrible for heat pump efficiency. With some great help from a heating engineer who installs these, we managed to reverse engineer the Modbus protocol, which is a way of logging data from the heat pump, and I'm now logging this into Home Assistant. That shows me how spiky things are: I have, just today, figured out how to revert to the Chofu room controller (ie cutting out the Honeywell and using the heat pump's own room thermostat) and am doing some experiments as to what difference it makes. Removing the Honeywell out of the loop completely is going to require some minor rewiring of pumps and valves, but I have just tried things temporarily as a test for now. I should get a better feel over the coming days. We also have some noise issues which might be being caused by TPI's constant switching on and off, or might be something else (there was terrible noise to begin with, because there was loads of air in the system). The heat pump is currently mounted next to the kitchen, so about a metre from the kettle with a window adjacent, which means it is audible inside. A family member is very noise sensitive so the contingency plan is to move it to the bottom of the garden, if my tinkering can't improve matters. From measurement the noise is in spec, but there are certain points in the spinup curve where it buzzes (another thing to investigate). Another thing is that Grant have switched from installing a buffer tank (that we have) to a low loss header. I'm sure some more plumbing-knowledgeable folks can comment on this, but I know plumbers familiar with the units are not impressed (read the Twitter replies) - I defer to more experienced folks, but seems to be just another thing Grant doing backwards to make it look like a boiler. One other thing is that the way Grant plumb in the buffer isn't good for doing cooling - it should work, but be less efficient. Investigating that is for another time of year... The Honeywell does have the ability to be controlled by an app, the Chofu natively doesn't*. Since I have Modbus up and running on Home Assistant I'm thinking of doing something in that area too, not sure quite what. I gather some of the other heat pump vendors are better in this respect. * Chofu the company also sells oil boilers and those can have controllers with apps which look very similar to the ASHP controller - maybe they will talk to it? But they would probably be in Japanese... On the flip side, it works, it heats, the hot water is great. On a cold January day (daytime maybe 3-5C) we're probably using 30kWh per day for heating, on a warmer one a lot less. So I think you can get a better outcome if you can avoid some of the installation problems (buffer not LLH, use the room controller or put in a smart thermostat that will run the heat pump for long periods not pulse it), use the heat pump to control the pumps and valves rather than the thermostat. I understand the price wholesale is quite good, which might be why installers like them. According to the Grant person on that Twitter thread: so it is something they are happy with, but your regular plumbing and heating engineer is going to install it like a boiler, and that's not so good. It works and all, but it could be better. Bottom line: would I do it again? Depends how much money is at stake. In our case we didn't have a lot of other options (the oil boiler had been condemned a year before and finally expired a few weeks before installation), and I think I probably would. Basically it was a calculated gamble, with various things I didn't know (noise, controls, cooling enablement) but thought were worth the risk, and some within my competence to address. I don't have final answers on those yet, but they are looking promising - I don't think there's any showstoppers. (In the worst case, moving it will be most work, but we get to rearrange the garden which needs doing anyway). On the other hand it has become a bit of a 'project' - if somebody was offering me an Ecodan for a few hundred quid more I probably would still take it (although it's possible noise etc issues would still apply)
  14. Fair enough, you can get a 6kW ASHP and cylinder delivered to your house for £3k. I ended up with a slightly more expensive one, like this. eBay - Mitsubishi 14Kw Ecodan Air Source Heat Pump with 300ltr cylinder - £9669.85
  15. Where do you get your numbers from? My ASHP plus cylinder, controller and other electrical and piping bits was £9k or so for the materials. I've looked and it's even more now. I spent £16k to get from no central heating at all to a fully working system commissioned to MCS standards with 13 radiators. Yes I had to pay up front but I'll get £11,300 back, CPI linked. I'm glad I got in before the end of RHI. And you need installers to know what they are doing; I wouldn't trust some local plumbers I've met to change a tap washer.
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