Posted by: @derek-m

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Posted by: @goody

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Posted by: @skd

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Posted by: @benseb

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Just to add, I’ve found my Ecodan excellent in this cold snap. It’s not faultered once and has kept us nice and warm. 

So if you can get the install and commissioning sorted, you can be reassured the actual heat pump is good (as long as corrrctly specced)

Yes definitely.  Excellent piece of kit so far,  now nearing first full yesr of service.  Not troubled at all by -8degC, snow, freezing fog etc recently.

 

I am green with envy 

I originally thought , 'great save the planet etc' now Putin is trying to destroy the planet - the energy crisis and the recent ' cold snap' has made me aware that all is not efficient with our heating system and it could be costing me an arm and a leg!

 

I may be wrong, but I think that the technical term for your heating system is 'Pig's Ear'. 😋 

The other thing that I forgot to mention is that if your 'calculated' heat loss at -3C is 8.1kW, then an 8.5kW heat pump is going to struggle below that temperature, even without a buffer tank or low loss header. Sorry to be the bearer of glad tidings.

 

I second what Derek says. The other thing to think about defrosting.  Your ASHP is working near its theoretical limit in these low temperatures.  If it's like mine (also an Ecodan) it will be defrosting every hour or so and this will reduce its output quite a lot.  Its average flow temp won't be what it is set at because it will drop every time a defrost happens.  There is also every chance it is never reaching the set flow temp, even momentarily, between defrosts because there isn't enough time before the next one happens. 

A lot of users find that ufh downstairs tends to heat upstairs without much help from radiators.  Have tried lowering the flow temp and allowing downstairs to get nice and warm and seeing if that warms up upstairs without the high flow temps you are running with now?     

@goody you do have a low loss header - straight from your schematic

Posted by: @goody

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The pipework run is around 3 metres with insulated pipe from pump to house up the house wall, however, since I posted I am thinking of getting some metal boxing and inulating the pipework more, as I can see metal valves uninsulated, and thinking about the workmanship i do not think it is insulated enough and now wondering if this could be a big big loss as I am typing...hmmm..

Since the Mitsubishi contractor telling me to ignore the weather compensation it is now on around 55C alteredfrom 58C last week. Heroes Ren told me to keep it at 48C....

Your positioning sounds fine. I would look to see if you have a full heat loss survey report as a pdf or an Excel document, then we could compare your radiators to the heat loss of the rooms. 

Insulating the pipe work further with UV stable insulation is a reasonable idea, but you must make sure you do not insulate over any freeze protection valves you may have. These are probably brass coloured and T shaped with the bottom of the T just being a hole. If you have glycol in your system you probably won't have these. 

On the weather comp I would enable it again, just with the coldest outside temp being at 55C flow temp, and try something like 15C outside at 35C. If you don't enable it you'll have higher than expected bills when it's warmer than it was last week. 

Posted by: @goody

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Posted by: @skd

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Are you using MelCloud?  If so, you can select the flow and return temperature curves (in Reports, select Hourly Temperatures) and you can see if your actual flow temperatures are achieving the desired set point.

I was never shown how to use MelCloud as the installer said it work differently, due to us keeping our exisiting radiator heating controls- 7 x Drayton Wiser radiator valves and underfloor heating controls- 5  x wired roomstats

 

Do you have the wifi interface, that enables remote access?  If you do then you can still download and set up the MelCloud app if you want to.  There are some helpful tutorials on youtube.

Posted by: @skd

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If you do then you can still download and set up the MelCloud app if you want to.

No need to download anything. A web version is available at https://app.melcloud.com/

Going back to some things written earlier: 600kWh so far this month is not outrageously high for an upgraded 1930s home IMO (ASHP gets expensive in subzero), although it is a bit more than I'd expect from what I've seen (including our own upgraded 1980s one), but it is outrageous if it's not keeping you warm enough! Our 8.5kW unit does, happily.

Oil may have been the cheapest fuel last week at 85p/litre average, but it's already now up to 95p/l. We never knew what we'd be paying once we had enough space to accept a minimum order quantity. And it's a foul polluting fuel and we've got to stop burning stuff sooner or later...

Posted by: @goody

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I was never shown how to use MelCloud as the installer said it work differently, due to us keeping our exisiting radiator heating controls- 7 x Drayton Wiser radiator valves and underfloor heating controls- 5  x wired roomstats

That, plus the words "controller installed in loft" on the schematic worry me. Are the Mitsubishi controls in the loft, or is the FTC panel somewhere else? If that's in the loft, I think you won't even be able to try the much-vaunted auto-adaptation mode (which has only just started working for me again in certain conditions, but others report success with it) without buying a Mitsubishi room temperature sensor (or control containing one). Corner-cutting muppets of installers! But weather-compensation should still be possible, even then, and the FTC seems pretty good at it.

As I understand it, the best approach with "foreign" controls like radiator valves is to use them only as protection against overheating a room, with the weather-compensation curve set to achieve and maintain the desired room temperature with the system balancing itself. The foreign controls shouldn't dictate the heat pump operation because they don't understand the Ecodan as well as its own controller. How much a Low Loss Header hinders the system balancing itself, I don't know.

Posted by: @oswiu

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Insulating the pipe work further with UV stable insulation is a reasonable idea...

You can get Class-O UV-stable pipe insulation from this link to BES.co.uk.  Never mind that they label it for 'solar' thermal pipes.

For interior use, their equivalent Class-O pipe insulation is here.

Class O nitrile rubber has a closed cell construction. Any rain or water-leaks can't impregnate the insulation layer itself.

You can slit-it along the length to slide onto a pipe, and then close the slit by using a contact adhesive (eg Bostik or UHU). On exterior pipe runs you still ought to seal any corner joints using Armaflex tape to prevent ingress of rain. Otherwise it can run between the pipe and the insulation, draining heat from the system.

Posted by: @mjr

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Posted by: @skd

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If you do then you can still download and set up the MelCloud app if you want to.

No need to download anything. A web version is available at https://app.melcloud.com/

 

Posted by: @mjr

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Posted by: @goody

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I was never shown how to use MelCloud as the installer said it work differently, due to us keeping our exisiting radiator heating controls- 7 x Drayton Wiser radiator valves and underfloor heating controls- 5  x wired roomstats

As I understand it, the best approach with "foreign" controls like radiator valves is to use them only as protection against overheating a room, with the weather-compensation curve set to achieve and maintain the desired room temperature with the system balancing itself. The foreign controls shouldn't dictate the heat pump operation because they don't understand the Ecodan as well as its own controller. How much a Low Loss Header hinders the system balancing itself, I don't know.

 

Posted by: @oswiu

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Posted by: @goody

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The pipework run is around 3 metres with insulated pipe from pump to house up the house wall, however, since I posted I am thinking of getting some metal boxing and inulating the pipework more, as I can see metal valves uninsulated, and thinking about the workmanship i do not think it is insulated enough and now wondering if this could be a big big loss as I am typing...hmmm..

Since the Mitsubishi contractor telling me to ignore the weather compensation it is now on around 55C alteredfrom 58C last week. Heroes Ren told me to keep it at 48C....

Your positioning sounds fine. I would look to see if you have a full heat loss survey report as a pdf or an Excel document, then we could compare your radiators to the heat loss of the rooms. 

Insulating the pipe work further with UV stable insulation is a reasonable idea, but you must make sure you do not insulate over any freeze protection valves you may have. These are probably brass coloured and T shaped with the bottom of the T just being a hole. If you have glycol in your system you probably won't have these. 

On the weather comp I would enable it again, just with the coldest outside temp being at 55C flow temp, and try something like 15C outside at 35C. If you don't enable it you'll have higher than expected bills when it's warmer than it was last week. 

 

The only heat loss calculation report I have is the one here:

I was going to see if someone made a box trunking for insulating the pipe further. We have chrome valves half way up the outside wall. I can not see any brass valves. I remember the glycol going in sas the installer spill about 5 gallons on the oak floor in our hallway! I was running around like a headless chicken mopping it up with dog towels etcs!

I ll go back to weather comp as you suggested, although the expected bills are alreasdy higher than expected!

Many thanks

Posted by: @transparent

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Posted by: @oswiu

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Insulating the pipe work further with UV stable insulation is a reasonable idea...

You can get Class-O UV-stable pipe insulation from this link to BES.co.uk.  Never mind that they label it for 'solar' thermal pipes.

For interior use, their equivalent Class-O pipe insulation is here.

Class O nitrile rubber has a closed cell construction. Any rain or water-leaks can't impregnate the insulation layer itself.

You can slit-it along the length to slide onto a pipe, and then close the slit by using a contact adhesive (eg Bostik or UHU). On exterior pipe runs you still ought to seal any corner joints using Armaflex tape to prevent ingress of rain. Otherwise it can run between the pipe and the insulation, draining heat from the system.

Posted by: @transparent

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Posted by: @oswiu

↑

Insulating the pipe work further with UV stable insulation is a reasonable idea...

You can get Class-O UV-stable pipe insulation from this link to BES.co.uk.  Never mind that they label it for 'solar' thermal pipes.

For interior use, their equivalent Class-O pipe insulation is here.

Class O nitrile rubber has a closed cell construction. Any rain or water-leaks can't impregnate the insulation layer itself.

You can slit-it along the length to slide onto a pipe, and then close the slit by using a contact adhesive (eg Bostik or UHU). On exterior pipe runs you still ought to seal any corner joints using Armaflex tape to prevent ingress of rain. Otherwise it can run between the pipe and the insulation, draining heat from the system.

Thanks