OVO heat trial - preliminary design

[SteamyTea]

Tell the installer to try out a minimum install on another property to save some cash. Then they can compare like for like.

 

These subsidies schemes are only selling you your own money back. Tossers.

Edited March 31, 2021 by SteamyTea

[Spoogster]

23 minutes ago, PeterW said:

So the installer is whining that a £250 buffer and £100 pump will be coming off their £5k budget for the install ..???! My heart bleeds... 

 

You have less than £5k of kit in there - the ASHP and tank are change of £4500 and I’m giving a generous £1000 for other bits which is well over the top. 
 

As I said .. this is a government backed money making scheme for installers ... 

that costing info is very useful. I am therefore going to push them very hard to add the buffer and pump in the cost and explain that Daikin strongly recommended. Daikin are a partner to the trial so I am going to push that too.

 

there are too many people in this world trying to make a quick buck regardless of the consequences...

[PeterW]

Ok so do a quick web search ..

 

https://www.cityplumbing.co.uk/Daikin-Altherma-EDLQ07CV3-7kW-Small-Monobloc-Air-Source-Heat-Pump

 

£2,600 inc

 

 

https://www.cityplumbing.co.uk/Daikin-EKHWSU300B3V3-Unvented-300L-Heat-Pump-Cylinder-%2B-Ekuhwbb/

 

£1,200 inc (although it’s 300 litre)

 

So my estimate was 10% out and that’s list price before discounts. 

 

 

 

[SteamyTea]

Who needs an ASHP, WSHP would work well here. Well when the tide comes back in.

 

[Spoogster]

27 minutes ago, PeterW said:

Ok so do a quick web search ..

 

https://www.cityplumbing.co.uk/Daikin-Altherma-EDLQ07CV3-7kW-Small-Monobloc-Air-Source-Heat-Pump

 

£2,600 inc

 

 

https://www.cityplumbing.co.uk/Daikin-EKHWSU300B3V3-Unvented-300L-Heat-Pump-Cylinder-%2B-Ekuhwbb/

 

£1,200 inc (although it’s 300 litre)

 

So my estimate was 10% out and that’s list price before discounts. 

 

 

 

Thanks Peter

[Spoogster]

During this hopefully short cold snap I decided to do a little experiment to see how our existing gas boiler system works assuming it is set at 45c, to mimic a heat pump system. My main concern is obviously whether or not the microbore supplied downstairs radiators would work ok and heat the home.

 

through today the outside temperature has been around 7 to 9 degrees. Our home is set at 19 degrees through the day. To date we have only run the gas boiler for an hour morning and four hours evening, again at 19c. For the experiment to mock up how the heat pump would be working through the day it has been running 0630 to 2100 hours.

 

I have also purchased a temperature digital thermometer from Toolstation of the probe type (£10). This appears to be accurate against other thermometers I have in the home.

 

I have managed to set the gas boiler to c45 degrees (quite a modern Worcester system boiler). First task was to see how the flow and return temperatures faired on the 22mm pipes direct from the rear of the boiler, for both the UVC recharge and rad heating cycles.

 

interestingly the heating flow is 45.9c and return 40.0c, which is very close to that delta t which a heat pump would operate (5c I understand) and less than the 10c I understand most gas boilers work to. The UVC cycle was bout half a degree greater so that delta t is about 6.5c.

 

the radiators in the ground floor which are fed by microbore seem to fair well. The single panel lock shielded rad in the hall was running at 44.5c so not much heat being lost en route to that one. The large two double rads in the living room at the opposite end of the house to the boiler were running at 42c or thereabouts, but these are the largest rads in the home. The living rads are well oversized though. 
 

so far the house has been very comfortable and the boiler has mostly been off. Taking off the hot water gas use I predict all day we have used 40kwh of gas, quite a chunk of which was in the morning getting the home from 16.5 to 19c (I would say 15-20kwh on that task alone). The real test will come on Monday and Tuesday when the temperature is going to drop to around 4-5 day but poss below zero evening.

 

I would appreciate thoughts on our measured delta t of less than six degrees, as to my kind it would appear our system retrofit could hack running at 45c without problem high delta t. Ok the pump is set on it’s highest setting but noise from the boiler itself is the only thing we can hear.  I am hoping our microbore is not going to be an issue, but if I am missing something please let me know.

 

obviously the Monday and Tuesday temperature tests will confirm if 45c will heat the house so an update will be forthcoming!

[SteamyTea]

If your weather has been like mine today, it was very sunny, and a light wind.  This will skew the figures to make them look better than the Delta T between inside and outside would suggest.

 

You will possibly find that your current boiler is not very efficient when at very low temperatures, it may not be condensing very well, but for checking the radiators it is a good test.

Hard to tell if the microbore will give a problem i.e. overpressure for flow rate with a heat pump.

How hard would it be to change those pipes after the ASHP is installed?  Would it be anymore work that changing them at the time?

 

Edit.

Just thinking about it, fitting a buffer should get rid of any pressure/flow problems.

Edited April 3, 2021 by SteamyTea

[Spoogster]

10 hours ago, SteamyTea said:

If your weather has been like mine today, it was very sunny, and a light wind.  This will skew the figures to make them look better than the Delta T between inside and outside would suggest.

 

You will possibly find that your current boiler is not very efficient when at very low temperatures, it may not be condensing very well, but for checking the radiators it is a good test.

Hard to tell if the microbore will give a problem i.e. overpressure for flow rate with a heat pump.

How hard would it be to change those pipes after the ASHP is installed?  Would it be anymore work that changing them at the time?

 

Edit.

Just thinking about it, fitting a buffer should get rid of any pressure/flow problems.

Thanks Mr Tea.

 

Yep I understand exactly what you are saying and ultimately I am going to impress on the installer to fit a buffer.

 

just to clarify the weather here in Kent yesterday was dull and overcast for all but about an hour in total around 3pm where the sun was intermittent. Stiff breeze all day making it feel colder than it was.

 

replacing the microbore would be difficult as it resides in the space between the concrete block wall and the dot and dab plaster board, so 15mm would be surface mounted and SWMBO would go nuts at that prospect! It would also mean lifting every floor upstairs and again modern construction methods mean large chip board floorboards - not easy. Definitely a buffer is the way to go. 
 

Will find out next week if the fitting company will play ball or just try to rip the arse out of the government funded scheme.

Edited April 4, 2021 by Spoogster

[Mattker]

Hi All, 

 

A really interesting thread a lot of which I think relates quite closely to my situation I'd be really keen to hear how @Spoogster has got on with the Ovo scheme installers, as as I say in my copies initial post below they didn't seem keen at all on our property as we have microbore plumbing throughout.

I've had some quotes and have got hold of the Freedom Heat pumps calculator and have had a play around with that. We're thinking of replacing a 20yo Gas boiler which obviously makes the cost/benefit calculation quite tight. It's existing microbore and we've had one suggestion of using a low loss header to help with the issue and another of using a heat exchanger so keeping the Radiator system and heat pump system totally separate, however the Ovo energy government trial being organised by Retrofit works in London dont want to use us unless we consider having all the microbore replaced with larger diameter pipework, as they say Daikin and Mitsubishi who are supplying the trial dont have any solutions to avoid potential noise and cold spots that they think the microbore may cause. Sorry for the lengthy post but I'm getting pretty confused at the mixed messages! ?

 

Any guidance from the wise heads on here welcome. Thanks 

[Spoogster]

On 11/04/2021 at 19:55, Mattker said:

Hi All, 

 

A really interesting thread a lot of which I think relates quite closely to my situation I'd be really keen to hear how @Spoogster has got on with the Ovo scheme installers, as as I say in my copies initial post below they didn't seem keen at all on our property as we have microbore plumbing throughout.

I've had some quotes and have got hold of the Freedom Heat pumps calculator and have had a play around with that. We're thinking of replacing a 20yo Gas boiler which obviously makes the cost/benefit calculation quite tight. It's existing microbore and we've had one suggestion of using a low loss header to help with the issue and another of using a heat exchanger so keeping the Radiator system and heat pump system totally separate, however the Ovo energy government trial being organised by Retrofit works in London dont want to use us unless we consider having all the microbore replaced with larger diameter pipework, as they say Daikin and Mitsubishi who are supplying the trial dont have any solutions to avoid potential noise and cold spots that they think the microbore may cause. Sorry for the lengthy post but I'm getting pretty confused at the mixed messages! ?

 

Any guidance from the wise heads on here welcome. Thanks 

I have found not all microbore is the same!

 

We only have microbore drops from the ceiling down to each rad, from 15/22mm pipes, and 15mm upstairs to all rads. The positive with our house is that we are judged quite energy efficient (year 2000 build) with new triple glazing four weeks ago and a shed load of new insulation in the loft in January (cost about £140 from B&Q. The installers were happy that the system should work and have confirmed today that they will be installing a volumiser buffer.

 

others on here are much more knowledgable than I so hopefully more input soon