Another 'Cool Energy' heatpumps thread

[HughF]

1 hour ago, JohnMo said:

If you can run Weather Compensation, do you need a room thermostat, just balance the flow rates to get the room temp you require.

 

If you have thermostats in the room, use simple ones to call for heat, but use them as limit stops, instead of a thermostat in the normal terms.  So if the WC is set to give you 20 degrees, set the thermostat at 22.

I’m planning to run full weather comp, the carel controller has a 4 point setting so it can be non-linear. I’m going to try without a room stat and just use TRVs in the bedrooms as hi-limit stats. I’ll program the flow temp to be set back at night and just leave the heating ‘on’ from Sept-April.

Nice and simple.

[JohnMo]

Spend last year learning about our building inertia when heating, and fixed a couple of issues with the buffer plumbings.  So now the boiler (min output 6.7kW), keeping house at an almost constant 20 degs.  UFH flow temp is 23/24 degrees during the day, boiler kicks in for about 10 mins every hour or so.  Night setback starts at 1830 hrs and goes back to day setting at 0230 hrs.

 

Working pretty efficiently, on average using 19kWh per day for 194m2 house including DHW (about 5kWh)  Against a theoretical 26 kWh for heating only, at our weather conditions using Jeremy's spreadsheet.

 

If I was heating with a heat pump with a CoP of 5, that would be 3kWh a day for heating only.  Super cheap.

 

[Marvin]

40 minutes ago, HughF said:

I’m planning to run full weather comp, the carel controller has a 4 point setting so it can be non-linear. I’m going to try without a room stat and just use TRVs in the bedrooms as hi-limit stats. I’ll program the flow temp to be set back at night and just leave the heating ‘on’ from Sept-April.

Nice and simple.

I had to move the sensor on the ASHP out of the sun to stop the under heating...

[HughF]

58 minutes ago, Marvin said:

I had to move the sensor on the ASHP out of the sun to stop the under heating...

Good idea…. I’m putting our ashp in the garden, shaded location with plenty of airflow, away from the neighbours 

[ReedRichards]

18 hours ago, HughF said:

 

My install will be a domestic retrofit running rads and UFH with a 150ltr slimline cylinder. I'm aiming for change out of £5k for all materials (ASHP, UVC, Pipe, Fittings, UFH mixer) and I'll be DIY'ing it next spring. Just got the new rads left to buy. We're replacing an 11kW Baxi Bermuda and heat loss calcs give 6.7kW at -3/21

 

 

Bear in mind that you will want to keep DHW cylinder at 50 C or less.  That's probably cooler than you are used to so when you run a bath you will use more hot water and less cold.  So you may want to use a larger volume cylinder.  You will also need one with a larger surface area coil than a conventional cylinder; that doesn't appear in your materials budget.  

[HughF]

11 minutes ago, ReedRichards said:

Bear in mind that you will want to keep DHW cylinder at 50 C or less.  That's probably cooler than you are used to so when you run a bath you will use more hot water and less cold.  So you may want to use a larger volume cylinder.  You will also need one with a larger surface area coil than a conventional cylinder; that doesn't appear in your materials budget.  

We’re upgrading from a 120ltr vented that we run at 55. I’ve already purchased the new cylinder, a vaillant slimline HP cylinder (the same as Glyn Hudson uses in his latest video). They were doing the rounds on eBay for £500 back in the summer. 1m2 coil. Pre-plumbed.

 

we can only accommodate a slimline cylinder in the cupboard.

Edited October 8, 2022 by HughF

[dpmiller]

1m2 isn't an enormous coil...

[ReedRichards]

17 minutes ago, HughF said:

We’re upgrading from a 120ltr vented that we run at 55. I’ve already purchased the new cylinder, a vaillant slimline HP cylinder (the same as Glyn Hudson uses in his latest video).

 

This is the Glyn Hudson who is "definitely not an expert"?  If the coil area is too small the cylinder will take a long time to reach temperature and the heating will be off during that time.  So if he/you have got it wrong then you won't know until it's a cold day in winter.  However the volume seems okay if your old cylinder worked for you.

[HughF]

9 hours ago, ReedRichards said:

 

This is the Glyn Hudson who is "definitely not an expert"?  If the coil area is too small the cylinder will take a long time to reach temperature and the heating will be off during that time.  So if he/you have got it wrong then you won't know until it's a cold day in winter.  However the volume seems okay if your old cylinder worked for you.

The Freedom heatpumps toolkit gives a recovery time of 120 mins….. 

 

It’ll be fine. If it wasn’t big enough, vaillant wouldn’t sell it with a 1m2 coil.

 

I don’t have a whole lot of options given my space constraints.

[HughF]

9 hours ago, dpmiller said:

1m2 isn't an enormous coil...

I know, but the slimline 150ltr offerings from world heat and McDonald weren’t a whole lot bigger. 

[dpmiller]

Just in case it's of use to anyone that has had an iVT unit in for a while, there is a software update that makes weather compensation a bit more user friendly (and some other functionality like run timers and legionella mode) for the 2020 machines.

[HughF]

54 minutes ago, dpmiller said:

Just in case it's of use to anyone that has had an iVT unit in for a while, there is a software update that makes weather compensation a bit more user friendly (and some other functionality like run timers and legionella mode) for the 2020 machines.

Interesting, cheers... I suspect mine has this installed already as it's a 2021 manufactured unit.

 

 

[dpmiller]

51 minutes ago, HughF said:

Interesting, cheers... I suspect mine has this installed already as it's a 2021 manufactured unit.

 

 

Have a look in the IO mask, the new version has all of the above there, whereas previously weather comp was buried in the hidden setup menu and the other items didn't exist at all

[HughF]

7 minutes ago, dpmiller said:

Have a look in the IO mask, the new version has all of the above there, whereas previously weather comp was buried in the hidden setup menu and the other items didn't exist at all

I’ll stuff a 13a plug on it and have a look… it’s sitting on my porch at the moment, at the house that doesn’t have mains electric, or central heating 🤣 Events of this summer (parents passed away, slightly unexpectedly) have put the brakes on my Somerset renovation until next spring.

[HughF]

52 minutes ago, HughF said:

I’ll stuff a 13a plug on it and have a look… it’s sitting on my porch at the moment, at the house that doesn’t have mains electric, or central heating 🤣 Events of this summer (parents passed away, slightly unexpectedly) have put the brakes on my Somerset renovation until next spring.

So I’m binge ordering stuff when I spot a bargain so I’m ready to roll when we do start on the extension and new heating system. Just got the rads and the underground pipe to buy now. 

[chrism0]

On 22/04/2022 at 22:18, dpmiller said:

I've gone for the TS/ ASHP and I contend it works perfectly well as long as you have the probe position correct and have a sufficiently large coil. Plus there's the possibility of other inputs like a boiler stove.

 

in actual fact I've gone direct for the stove, and indirect for the ASHP.

Hi Dave have dropped you a wee PM there sir about this setup, would love some details!  Cheers

[dpmiller]

11 minutes ago, chrism0 said:

Hi Dave have dropped you a wee PM there sir about this setup, would love some details!  Cheers

I'll get some ideas together and get back to you over the weekend

[chrism0]

2 minutes ago, dpmiller said:

I'll get some ideas together and get back to you over the weekend

Thanks appreciate it!

[HughF]

Had to condemn the back boiler due to a ventilation issue….

 

Just had a week off the day job getting it installed with my builder. Been a long week of self doubt (will this keep us warm?) and sleepless nights but I think we’re over that now.

 

All new pipework throughout, rads sized for 45 deg at -4, three Smiths Ecovector fan coils where we didn’t have space on walls for larger radiators.

 

I did heat loss calcs in two separate packages, the freedom toolkit and heat engineer. They both came out around 6.8-7kW at -4, with the old double glazing (we’re replacing that at the moment) and the uninsulated timber floors (which we start on on Monday). 
 

Lagging, thermostat, and some more lagging to do tomorrow.

 

All parts and my builder for a weeks day rate, just got change out of £12k. More than I thought, but the rads came to £1200 and the ecovectors were £1400….

 

I haven’t bothered to calculate a payback period, we needed a new heating system, and if these rads and pipework last as long as the last system (installed in ‘86 by the council, after the previous coal fired boiler had done 40yrs) then I’ll be happy. At least that’s 18-19000kWh of gas (our average annual consumption) that we can leave to be burnt in a ccgt. I’m thinking we’ll swap an £1800 gas bill for £1200 ish uplift in the electric bill, before we even consider solar and battery.

 

Oh and to anyone thinking that hi-line eFlex underground pipe is flexible, it isn’t….. what a sod to install.

Edited September 30, 2023 by HughF
More ramblings to add

[JamesPa]

2 hours ago, HughF said:

Oh and to anyone thinking that hi-line eFlex underground pipe is flexible, it isn’t….. what a sod to install.

Would you be willing to share more about your experience with this stuff?  It (or something similar) remains an option for me if I can't convince myself that the more obvious location next to the house won't annoy the neighbours.

[HughF]

17 minutes ago, JamesPa said:

Would you be willing to share more about your experience with this stuff?  It (or something similar) remains an option for me if I can't convince myself that the more obvious location next to the house won't annoy the neighbours.

All I will say is that when you cut the straps off the coil, it doesn’t uncoil. It took three of us to unravel it and get it into the trench. Very difficult thing to do. I think it’s because the pex pipes are bonded to the pir insulation, and that’s then bonded to the outer casing.

 

I dug 900 down, and it still came out the ground at 45 degrees at one end). The good news is that 32mm mlcp press adapters will fit onto the end just fine, although the kit comes with compression BSP tails that you can assemble with hand tools.

Edited September 30, 2023 by HughF

[JohnMo]

The other option is two ducts, one supply the other return. Use 110mm twin wall flexible duct, Hep2O pipe or similar, with 25mm thick Armour-flex. Seal the ends of the duct as it comes out the ground spray foam and stainless steel mesh. Still a pain to bury but less so than above.

[HughF]

On 30/09/2023 at 21:56, JohnMo said:

The other option is two ducts, one supply the other return. Use 110mm twin wall flexible duct, Hep2O pipe or similar, with 25mm thick Armour-flex. Seal the ends of the duct as it comes out the ground spray foam and stainless steel mesh. Still a pain to bury but less so than above.

Yeah, I’d advise going for two ducts if you ever decide to do something like this…

[JamesPa]

On 30/09/2023 at 20:56, JohnMo said:

The other option is two ducts, one supply the other return. Use 110mm twin wall flexible duct, Hep2O pipe or similar, with 25mm thick Armour-flex. Seal the ends of the duct as it comes out the ground spray foam and stainless steel mesh. Still a pain to bury but less so than above.

Thanks.  Just to understand precisely, in this suggestion the insulated water pipe runs loose in the duct, surrounded by air (or water if water somehow gets in, which presumably needs to be avoided). 

 

It does sound simpler than the prefabricated twinpipe.

[JohnMo]

Yes runs loose in the outer duct. There is an air space, between the outer of the insulation and inner of the outer duct. I actually wrapped the insulation in aluminium tape also. The armour flex is close cell foam so shouldn't absorb water, the outer casing is mechanical protection and stops the insulation being compressed by the weight of the soil, sand etc.