Going from Coal to Air Heat Source Pump and PV's using ECO4 grant scheme

matt_drummer

shinytop said:

@Pec123 has been quoted for an 8.5kW Ecodan.  If you read their posts, the 14kW refers to the maximum output from the Ecodan range, not their specific quote.  That sounds about right for the house described. 

I agree about the design flow temp being too high.  Having said that, remember that it will only use 55 deg when it's -3 deg or whatever.  Most of the time it will be much lower. 

Thanks.

I find it difficult to read as presented, one minute about solar panels, then flitting to heat pumps, heat loss of 14.5kW or 8.5kW, and then quoting the power output of heat pumps they are not getting.

I don't know how they information is being extracted but it has confused me.

Thanks for pointing it out.

Reed_Richards

I've been tryng to understand the radiator types.  A company called Kartell makes K-Rad radiators: 
https://kartelluk.com/categories/panel-radiator

There is also a brand called CenterRad:
https://www.wolseley.co.uk/brands/centerrad/

I don't know why you would mix types from two different manufacturers, unless it's just the ones they have in stock at the moment

Reed_Richards

This is my interpretation of your data (but I could be wrong)

Room	Heat loss?	H x L	Type	Manufacturer	Divisor	Output	% of required
dining room	725	700x1600	k2	centre rad	1.9 (HEG)	1682	232%
kitchen	824	700x800	k2	centre rad	1.9 (HEG)	831	101%
bedroom 1	490	400x1400	p+	Not stated	1.9 (HEG)	760	155%
lounge	822	400x1400	k2	krad	1.9 (HEG)	982	119%
hall	253	600x1000	k1	centre rad	1.9 (HEG)	499	197%
bathroom	663	600x1000	p+	centre rad	1.9 (HEG)	704	106%
bedroom 2	404	600x1000	k1	krad	1.9 (HEG)	500	124%
bedroom 3	587	600x1600	k2	centre rad	1.9 (HEG)	1488	253%

Reed_Richards

In order to use a lower flow temperature and cut your costs the two difficult rooms to deal with are the kitchen and the lounge.  These are already specified as k2 radiators and you would need a larger output in both cases.

Kitchen: Is there room for a larger radiator, perhaps a vertical one that is 800 cm long but, say, 1400 cm high?

Lounge:  Is there room to fit a bigger radiator, like the one intended for the dining room?  Or if not, is there room for a second radiator?

FreeBear

Reed_Richards said: Kitchen: Is there room for a larger radiator, perhaps a vertical one that is 800 cm long but, say, 1400 cm high?

A plinth heater would take up no room and potentially double the heat available. Yes, they are expensive and may need a modification to work with low flow temperatures (changing the thermal switch inside to a lower operating temp).

Side note - There is a big jump in radiator prices once you go above 1200mm in length. And I'd be questioning the need for such a big one in need for bedroom 3.

Reed_Richards

I've always been concerned about that thermal switch inside a typical plinth heater rendering it incompatible with the low water temperatures produced by a heat pump.  Do you really think it is feasible to change it to a lower temperature, @FreeBear?

As for radiator costs, the OP is getting the whole thing for free under the ECO4 scheme so that's not their problem.  I have no idea how a budget is set for the company doing the installation.

FreeBear

Reed_Richards said: I've always been concerned about that thermal switch inside a typical plinth heater rendering it incompatible with the low water temperatures produced by a heat pump.  Do you really think it is feasible to change it to a lower temperature

Have a Smiths plinth heater here. Swapped the thermal switch out for a lower rated one a couple of years back. Quite easy to do - The hardest part is finding one that will operate at the desired temperature. Not a huge selection under 40°C, but I have found one Chinese supplier on ebay listing switches that operate at -15°C.

The other option is to link the fan to the CH pump. Alternatively, fit a smart switch that can be controlled via a home automation system.

Reed_Richards

For the benefit of the OP, a plinth heater is fan-assisted radiator that fits below a kitchen cabinet in the plinth space.  Because it has a fan it can be a little noisy but then kitchens tend to be quite noisy anyway.  The fan boosts the heat output so you get more heat than you would get from a normal radiator of the same size.  The problem is that the fan is activated by a thermal switch and the activation temperature is typically when the water temperature reaches 50 C.  That's too high to work properly with a heat pump.     

Pec123

Thank you all for your valuable feedback. I have choosen the company with the Mitshubishi ASHP. However, as some quite technical questions have been raised I have attempted to contact the Technical Job Manager with a long wait for Customer Service and told this is indicative of this company. Should I source another company as I thought with this sort of thing with Customer Service was quite important? I'm sure the heating system would affect our house price so this is an investment. So I prefer to chew it over before the work starts. What do you think?

QrizB

Pec123 said:

What do you think?

In all honesty, they're an installer. You shouldn't need any technical support from them once the system is installed, and if you do have questions, it's probably better to email them and get a reply in a couple of days.

What questions do you have? Could you list them here?