Hello from Northumberland!

[Remington]

Heya,

Just stumbled on this amazing resource in a completely unrelated search and had to register immediately as theres so much good stuff on here.

We're based up in northumberland, we have a house and a .13 hectare garden (iirc) on a 38 degree slope, its a bit challenging

i'm really enjoying building stuff, primarily of timber, last year the lockdown project was a 2.4x4.8 workshop, this years has been a retaining wall and will be a 2nd shepherd hut as a home office.
 

The search that brought me here was actually a 2017 thread covering heat loss calculations, as we're looking at a heatpump for our EPC E house, not such a joy project

[SteamyTea]

11 hours ago, Remington said:

looking at a heatpump for our EPC E

Going to be a large heat pump.

What can you do to reduce the heat load of the property.

[Remington]

yep, 12kw at least is the initial quotes we've had, and solutions start getting ugly at that size.

What can we do? tough one, its double glazed and roof insulated but the mixed mode of building evolved over 200 years has left a right mess to try and insulate and get rid of the biggest problems without utterly destroying the living conditions at the same time.

Current plan is to get a full heat loss calc so we at least have a baseline understanding of the 'worst' case and we can then start building up from there.

[saveasteading]

9 minutes ago, Remington said:

get a full heat loss calc

That may not be pleasant reading, but essential information before that commitment.

 

If someone has suggested 12kW then they have presumably estimated your current or proposed  heat loss.

There is a heat loss programme in Buildhub somewhere, created and gifted by a clever member.  Others can point you to it, as I can't find it for the moment.

 

It  will let you play with options and see what is worth doing.

 

FYI we are building 400m2 (conversion but effectively new-build) and will have an aggregate of  16kW ASHP.

That may give some comparison to your building's efficiency.

 

[Remington]

25 minutes ago, saveasteading said:

That may not be pleasant reading, but essential information before that commitment.

 

If someone has suggested 12kW then they have presumably estimated your current or proposed  heat loss.

There is a heat loss programme in Buildhub somewhere, created and gifted by a clever member.  Others can point you to it, as I can't find it for the moment.

 

It  will let you play with options and see what is worth doing.

 

FYI we are building 400m2 (conversion but effectively new-build) and will have an aggregate of  16kW ASHP.

That may give some comparison to your building's efficiency.

 

 This was actually what lead me here , but the site and excel calculator seems to be offline now

the house has solid stone, solid brick, a small amount of empty cavity, areas with no dpc foundation, dubious decisions made on pipe, electrical runs as well as insulation choices. typical old extended house i guess

based on your 400m2 example, ours is closer to 200m2, and the installers i've managed to talk too have all listed 12kw minimum with potentially 2x7kw running in sequence which naturally need £ of additional electrical changes to carry that much load etc etc.

[SteamyTea]

4 minutes ago, Remington said:

potentially 2x7kw running in sequence

Probably not as efficient as running one larger HP.

ASHPs have better efficiency at part load. The idea is to not run them too close to maximum.

 

Think this is Jeremy's spreadsheet.

Heat loss calculator - Master.xls

[Remington]

fantastic! thanks @SteamyTea i couldnt find a working link when i browsed the thread - this could be due to tablet browsing mind (just occured to me).

[saveasteading]

3 hours ago, Remington said:

£ of additional electrical changes

ProDave needed to explain this perhaps, but you may not need more power.

 

15kW output needs something like  4kW electric supply.

Most houses are using less power because of LED lights.

Do you know what power you have available? On your bill, or see the fuse.

 

Now you are among us you must promise to use capitals for any famous scientist recognised in the terminology. So kW ,  kVA , kN etc.

 

On a positive, to my surprise solid stone walls have been found to be a better insulator than the calculations allow.

In our reg's application we inserted a figure for it from these studies (we have 600mm of granite) and it was accepted (though perhaps not noticed).

[Remington]

The house has a 100amp fuse, and we’re consuming between 12kWh and 30kWh per day with current use, depending if the car is plugged in to charge.

 

gas usage is still manually collected, but the electric house consumption has been tracked in home assistant since bulb made the smart meter work again. That said we haven’t used the gas for anything since 14th of may.

good news on the stone walls though!

 

 

1 hour ago, saveasteading said:

ProDave needed to explain this perhaps, but you may not need more power.

 

15kW output needs something like  4kW electric supply.

Most houses are using less power because of LED lights.

Do you know what power you have available? On your bill, or see the fuse.

 

Now you are among us you must promise to use capitals for any famous scientist recognised in the terminology. So kW ,  kVA , kN etc.

 

On a positive, to my surprise solid stone walls have been found to be a better insulator than the calculations allow.

In our reg's application we inserted a figure for it from these studies (we have 600mm of granite) and it was accepted (though perhaps not noticed).

 

[saveasteading]

2 hours ago, Remington said:

30kWh

Average 1.25 /hour, and you have 24kVA.

  100A x 240V = 24000 VA = 24kVA.

Sounds like plenty.

Somebody else check please.