Heat Pump Sizing?

Reed_Richards

Spies said:

I have gas data from when we had that period of sustained minus temperatures, is this a good indication of heat loss?

Yes and no.  It's a good indication of the heat loss during that period, although you'll have to guess the efficiency of your gas boiler.  You can work out an average room temperature, an average outside temperature and an average heat loss power.  Your MCS heat loss evaluation will give you an estimated heat loss at some particular outside temperature, probably assuming you are heating your house to 21 C.  So you could compare the two figures and see if they stack up.        

michaels

You also need to consider whether the boiler was also heating your hot water during any of those periods.

Boiler efficiency will also depend on whether your boiler is running constantly at those output levels or cycling on and off.

michaels

So most of the heat pump companies suggest about 6.5-8.5k after grant as an initial estimate.  I then got one to go into more detail and they came back with 20k after grant.

Sadly it looks like I will be fixing the gas boiler or failing that, replacing it

I really think I could purchase the parts and get a plumber to install for way less even with no grant then being payable.

Heat pump 7k
9 Rads 1.6k plus 0.9k fitting (all but one don't even need the valves moving)
300l cylinder £1.5k

(These prices include VAT, is VAT even chargeable on heat pump installation?)

Cylinder can simply be swapped with old one
HP indoor 4 pipe unit can be swapped with existing 4 pipe boiler
Heat pump to be mounted on external wall with approx 10m cable run to consumer unit and 3m pipe run to indoor unit (they can even use existing flue hole in external wall for pipes)
Weather comp controls so nothing complex in that direction.

I must be missing something

Spies

Octopus is usually the lowest for quotes, what did they say?

michaels

Spies said:

Octopus is usually the lowest for quotes, what did they say?

4k with fewer rad changes and a heat pump model and position I don't want - but for 16k less perhaps I can live with a less than efficient and attractive solution....

Spies

You can always change out the other rads yourself I guess and still be quids in!

wrf12345

There does not seem to be any incentive to fit the simplest possible system, rather endless complication to ramp up the cost, the grant seen as a nice bonus for the installer rather than saving the consumer real money. Octopus the best of a bad bunch but not yet installing everywhere in England, and even there it is more a tick-box installation than a carefully crafted system to max out efficiency - but, hey, they make money out of selling electricity.

matt_drummer

wrf12345 said:

There does not seem to be any incentive to fit the simplest possible system, rather endless complication to ramp up the cost, the grant seen as a nice bonus for the installer rather than saving the consumer real money. Octopus the best of a bad bunch but not yet installing everywhere in England, and even there it is more a tick-box installation than a carefully crafted system to max out efficiency - but, hey, they make money out of selling electricity.

Give us a run down of how much it would cost and how long you think it would take to ft a heat pump to an average 3/4 bedroom house with a heat loss of say 6kW.

Give us a breakdown of the components you would need and the cost making sure it complies with MCS requirement to ensure receipt of the grant.

Give us something positive and constructive for a change @wrf12345 rather than the constant negativity.

matt_drummer

Here is my attempt.

Prices exclude VAT 

Labour is priced based on employees having usual employee benefits and the cost of providing transport and tools

An electrician for two days and two installers for four days.


Daikin EDLA08E2V3 heat pump £3,750
Joule 200l hot water tank £1,050
Heat pump base £100
Copper pipe and fittings £450
Pipe insulation £200
Trunking £200
Flexi pipes £150
Electrical components £250
Plumbing items (filters, valves etc) £400
Anti frost valves £100
Waste disposal £100
Sundries for making good such as paint, filler, plaster etc etc  £250

That is £7,000 for components excluding VAT

Labour would be ten people days @ £500 so £5,000 in total excluding VAT

Then allow £1,000 for survey, design, administration (MCS, building regs etc)

Conservatively this is £13,000 with no allowance for profit, things like insurance, putting stuff right etc etc.

I paid Octopus £6,500 so with my grant of £5,000 they got £11,500 in total.

For that they actually installed a more expensive Daikin heat pump initially and have since replaced it free of charge for the one above.

I also had two radiators changed, one 600 x 1600 K2 and one 450 x 1800 vertical K2. They also had to replace the end panel on the vertical K2 but instead of sending the end panel they just sent another new radiator so now I have a spare.

I had a survey (that took all day basically including travel for the surveyor), a pre install visit, for employees at my house for five days (so twenty working days in total), two post installation visits, one to check the install and clean filters and another was an MCS audit requirement. My lead installer came from the other side of the country so had to spend five nights in a hotel. Octopus had to pay for that because they were committed to the job. They have to have spare staff to cover unexpected events, otherwise it would never work.

I also had another survey carried out after installation plus two visits from Daikin engineers.

Octopus buy in bulk so their costs will be lower than above but not that much. They make very little if anything. They are certainly not just adding the grant onto the actual cost and keeping it.

An independent heating engineer would have costs similar to those listed above


So, @wrf12345, tell me what's wrong with the cost?

How would you do it for less?

Even just the materials will cost you £8,400 including VAT if you did all the work yourself.

michaels

Here is my attempt:

12.5kw 'Dream' heat pump £1600

Pipe and sundries to put this into the current heating circuit £500

SWR cable, fuse unit £100

Labour supplied by me

DHW left on immersion

12mwh of heating per annum now supplied by heat pump at cop of 3 using battery storage of overnight electricity at 9p per unit (7.5p but round trip losses and some peak usage) = 3p effective per kwh of heat compared to gas at 6.2p per unit gives a saving of 12mwh x (0.062-0.03) = £384pa saving

Get slightly cleverer and also use it to do the 7mwh annual hot water and that increases by another £224 per year.