Additional electricity load on home with GSHP

[8Coops8]

Looking for some advice. I currently have single phase electricity supplying my refurbished home but am now looking to install a GSHP to replace my old oil boiler and also a car charging point.

My electricity supply is already pretty much maxed out and I require more power. It appears that I already have 2 single phase cables entering my home but only 1 live cable enters 1 of 3 100Amp fuses and then goes into my electricity meter, so presume 2nd single phase supply was never connected. The electricity pole supplying my house has 2 pairs of black cables (4 cables total). I contacted Northern power and received the following "A load of 35.00 kVA may be connected providing the load is split and balanced over the two phases available and your connected load does not exceed 80A per phase at any time. The connection is a low voltage 230/460V alternating current 50Hz supply. The present earthing arrangements will be maintained. If your metering requires upgrading or you require additional meters fitting, your supplier is responsible for carrying out this work."

I then contacted EON and they don't know don't seen to understand my meter requirement and keep asking if I want a single phase meter or a 3 phase meter as there is no such thing as a 2 phase meter...?

Anyone any idea what I would require?

 

Thanks

[JohnMo]

There are only single or three phase, as far as I am aware, so you are really asking for two single phase meters.  Double the standing charge of a single meter.  No wonder they are confused.

 

You seem to indicate you have there 100 amp fuses, only one is being used.  So did your house at some point have 3 phase, hence the three fuses?

 

 

[SteamyTea]

Didn't using 2 of the 3 phases used to be called 'split phase.

Was fairly common in small farms.

 

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=38062

 

[8Coops8]

Definitely never had 3 phases. 

[8Coops8]

I think the 2nd single phase powered an outdoor swimming pool until it was removed about 40 years ago. The 3 fuses were installed about 7 years ago when i relocated the incoming power supply. Would like to put both single phases into a 3 phase meter ideally to save the additional standing charge, but can you do this..?

[ProDave]

Split phase is uncommon now, it is essentially a single phase supply, but derived from a centre tapped 460V transformer.  You have a 3 phase supply head with 3 fuses as that is standard equipment, one will be unused.

 

How do you know if the second feed is not live?  You would have to break the seal on the fuse to determine that?  Or is it connected to something?  A picture of what you have might be interesting.

 

As far as your supplier is concerned, get a 3 phase meter.  The may or not connect the "3rd phase" but they might?  It won't do anything.  A 3 phase meter will ensure you only have one MPAN and only pay one standing charge.

 

Because it is so unusual, all I can suggest is you ask your supplier for a 3 phase meter and see what the meter man says when he turns up.  Have a second single phase CU raeady to connect it to.

[8Coops8]

[8Coops8]

[Carrerahill]

2 hours ago, 8Coops8 said:

My electricity supply is already pretty much maxed out and I require more power.

How have you calculated this? Have you applied diversity and or done a load analysis?

 

 

[8Coops8]

The proposed installer of the heat pump had a look at my current appliances and thought it a risk without approval from the power grid; mainly due to peak amps on start up ~52A, they confirmed i required additional load. I have all electrical cooking appliances; heat recovery ventilation and a hot tub already using up the supply.

[ProDave]

9 minutes ago, 8Coops8 said:

The proposed installer of the heat pump had a look at my current appliances and thought it a risk without approval from the power grid; mainly due to peak amps on start up ~52A,

STOP RIGHT THERE.

 

A high start up current like that means this is not an inverter driven ASHP.  Before you think of upgrading your supply, choose a different, inverter driven ASHP that will have soft start and will modulate it's output to match demand.

[jfb]

Why are you wanting a gshp and not an ashp? 
Lot more effort for the gshp for little extra benefit I would say. 
what is the power consumption of the house at the moment (heating and water)?

Edited June 13, 2022 by jfb

[8Coops8]

Heating consumption is ~38000KW; measured by oil consumption so probably 33000KW if 100% efficiency. Max heat loss at -5C outside and 21C inside is ~15KW; as measured by timing oil boiler firing over 12hr period at consistent 0C outside and then extrapolating to -6C.

i live 2 miles from the sea and we can get severe fog almost daily in some years and was worried about ASHP having freezing problems.

GSHP was to use boreholes and don't like the cost but figured it would be more reliable.

[joth]

28 minutes ago, 8Coops8 said:

Heating consumption is ~38000KW; measured by oil consumption so probably 33000KW if 100% efficiency.

 

I expect you mean kWh, not KW, for those two numbers, if that is annual consumption?

[8Coops8]

Yes kWh and annual consumption

[Wil]

Aren’t the 4 cables on the pole L1,2,3 and N? Can’t you just ask your DNO for a 3phase upgrade unless the other phases are used for something else. If two of those black wires enter your property, Shirley this is L and N?

 

Have DNO confirmed only 2 phases available? You only have L&N on your internal photo unless other phases are terminated in the fuse box chamber?

 

 

[8Coops8]

DNO say 2 phases available inside my property and i can see 4 wires combine at pole and go underground and into my house, but currently only 1L and 1N is connected to the fuses and meter. So assuming 2L and 2N. I wonder if historically there were 2 meters fed from the 2 single phases.

[RobLe]

Perhaps you could consider EWI, to get that 33MWh/year heat load reduced, whatever the heatsource.  While the cost difference between a small gas or oil boiler to a high power one isn't that great - that difference will be very significant for a gshp, and also (to a lesser extent) with an ashp.  Have you had a quote or estimate for the gshp? 

I would expect the price saving from a 15kW gshp down to a 5kW heatpump will cover most of the cost of EWI, and the ongoing elec bills will be much smaller too.

GSHP often have simple (more reliable but perhaps not quite as efficient) on/off compressors, I think mainly as there's less of an issue with external audible startup noise than there is with an ashp.

None of the above is a reason not to get three phase by the way, get it if you can. 

 

[8Coops8]

I already have EWI; all heat saving measures possible have already been carried out to allow for low temperature heating. Its just a very big house ~440m2. Its a 250yr old house that i fully refurbed with energy consumption in mind but money stress meant i left the original 50-70kWh oil boiler in place until now.