ASHP do you need to apply to electricity supplier for increased load?

[alirus]

We're about to take the plunge and install an ASHP (11kw Daikin Altherma HT). Someone said that we'd need to apply to the electricity supplier requesting an increased load. It is a single phase system we'll be installing. Has anyone had to do this and if so how much does it cost? The costs keep spiraling up and we're already well-over our initial budget

[r.bartlett]

ask your electrician

[our v]

hi there fitted a few of these not heard of that one before

[chilliwilly]

If its a home that your installing the system in, you will more than likely have a 80-100 amp 230/240v service in your home. Is the rating of the heat pump 11kw input power or output power, if it's input then your electrical service should have sufficient capacity to cope with the demand, allowing for diversity. If your service hasn't got the capacity and its reaching its maximum load demand 18.4-24kw, then yes you will need to up the service size. But you will have to contact your area board/electrical utility provider for a quote. They usually get you to fill out a form stating your exisitng total demand. A few years back, I wired a 6 bed new build, and I worked out the total demand to be around 43 kw and requested a three phase supply to be installed. But they calculated it to be less than that and they said that the existing 100 amp 24kw supply would be adequate. So they just quoted to move the meter and service cut out. The total demand that I calculated including diversity was to include 6 x 11 kw showers and a small sauna. The house was only ever occupied by three people at the most, and as far as I know the service fuse never blew. But I would still reccomend your area board to do a survey as regulations/codes do change and not always for the better.

[sinewave]

You'll be fine OP

We have a 16kW HT in our house and it never peaks at much more than 9.5kW max electrical loading.

FYI

I also used to work for our local DNO (District Network Operator) Scottish Power.


It may surprise you to learn that typically the DNO
would only rate the electrical demand in a 'standard' 3 bed
house with Gas CH at around 2.5Kw.

After diversity, calculated demand is less than one kW! :eek:

That's diversity applied to Network cabling over 100's of houses though.

Each individual house could have a maximum demand of 2.5 kW, but this is the MDas defined by the DNO. Their definition of kW MD is twice the number of kWh inhalf an hour.

i.e The integration periodis 30 minutes.

The integration period for a DNO's distribution network works satisfactorilybecause transformers, switchgear and network cables used by a DNO do notoverheat unless an overcurrent is sustained over half an hour or more (i.e. not a fault current!).

The volatility of the thermal characteristics of the domestic wiring in a house is much faster and a half hour integration period is then far too long.

A shorter integration period means that the maximum demand of the house would be significantly higher. You are now talking about 5 to 8 kW instead of 2.5 kW.


In conclusion DNO supply cables and their BS1361/88 fuses will take massively more abuse without detriment than you'd think so save your money and carry on regardless!