Are Heat pumps worth it

[SteamyTea]

5 minutes ago, PeterW said:

Benefit of gas

COP 27 is not going to be of any interest to you then.

Edited November 4, 2022 by SteamyTea

[PeterW]

11 minutes ago, SteamyTea said:

COP 27 is not going to be of any interest to you then.

TBH this is a system design to meet a basic requirement - I would put in an R32 ASHP but again I wouldn’t look at the short term plan if this wasn’t about a  saleable property. As I’ve said though - I’ve got minimal info so it’s a lot of guesswork 

[Iceverge]

18 hours ago, deuce22 said:

It is a new build constructed from Nudura ICF, 150mm PIR in floor, warm/hybrid roof with 150mm PIR, 200mm mineral wool between rafters.

 

 

 

This sounds like a very good spec. 

 

Just a few questions 

 

How thick is the ICF?

What are your airtightness targets? 

What is your glazing situation including number of windows and orientation?

 

What is the shape of the house? A simple 360m2 box may have a surface area of 750m2 whilst an awkward series of interconnected bungalow's might be double. 

 

[ReedRichards]

3 hours ago, deuce22 said:

ReedRichards

So how many KW over the year do you think you save through solar? 

 

According to my inverter in 2021  I used 10714 kWh of which I generated 2862 kWh, about 26.7% of the total.  My meter says I imported about 8200 kWh in 2021, my inverter thinks it was 7852 kWh so that's broadly correct.  The heat pump used 6026 kWh.

 

In summer I use spare solar electricity to heat my water but I use the immersion heater because its power requirement, 3 kW, is better matched to my solar output.  

[deuce22]

PeterW

Due to what has been discussed here and from my own experience I don't trust what any tradesmen say, Ive been ripped off a couple of times and also been talked into doing some things that I now realise is not the right way and has cost me more money to correct it. I will be in this property for at least 5 years, but nobody knows whats around the corner, I could be here longer. I want it to be as comfortable and as efficient as possible for whilst I'm living here, but also want to do it in the best way for anybody that buys it in the future.

Is there a big benefit to having 2x 180l over 1x 300l?

 

Iceverge

ICF is 67mm in and out. I was either going to use Nudura or Jackon. The salesmen for Nudura told me that 67mm is the exact amount that is needed and any thicker is a small return on investment. Jackon ICF was 50mm inside and up to 200mm outside, when I mentioned this to Nudura they said it wasn't needed. However, Nudura has now added another system that incorporates thicker insulation on the outside, so he was obviously talking crap.

I haven't even looked into air tightness.

There are quite a few openings. Out of 254m2 of external walls, 64m2 are doors and windows.

It is an equal L shape.

 

ReedRichards

Is the 2862 kwh, the same as 2862 units of electric?

 

 

[SteamyTea]

4 hours ago, deuce22 said:

ReedRichards

Is the 2862 kwh, the same as 2862 units of electric?

Yes, and the same as 2,862 kWh of natural gas, gasoline, timber or coal.

A kWh (not kwh) is derived from SI units for distance, mass and time.

The real unit of energy is the joule [J] and is very small, the force needed to move a kilogram 1 metre.

If you move that mass and distance in 1 second, then it is known as a watt [J/s]

If you carry on doing that work for 1 hour, then that is a Wh.

 

 

It is often easier to think of energy as gasoline or diesel in your fuel tank, and the engines power is the rate that you use up that fuel.

 

[ReedRichards]

1 hour ago, SteamyTea said:

A kWh (not kwh) is derived from SI units for distance, mass and time.

 

I'm not sure an hour is an SI unit.  There's an amusing article here: https://www.electronicsweekly.com/blogs/electro-ramblings/weird-wireless/weird-wireless-how-did-we-end-up-with-a-kilowatt-hour-2009-08/ .  Personally I would rather have mega joules. 

Edited November 4, 2022 by ReedRichards

[SteamyTea]

8 hours ago, ReedRichards said:

Personally I would rather have mega joules

So would I.

[ReedRichards]

16 hours ago, deuce22 said:

It is an equal L shape.

 

 

So even further from one end to the other than if it were a box.  You'll need to take some pains to avoid long pipe runs for your hot water.  

[Iceverge]

On 04/11/2022 at 17:19, deuce22 said:

ICF is 67mm in and out. I was either going to use Nudura or Jackon. The salesmen for Nudura told me that 67mm is the exact amount that is needed and any thicker is a small return on investment. Jackon ICF was 50mm inside and up to 200mm outside, when I mentioned this to Nudura they said it wasn't needed. However, Nudura has now added another system that incorporates thicker insulation on the outside, so he was obviously talking crap.

I haven't even looked into air tightness.

There are quite a few openings. Out of 254m2 of external walls, 64m2 are doors and windows.

It is an equal L shape.

 

As you've deciphered sales men are full of sh*t. 

 

I got terminally confused by all the marketing nonsense so I sat down with a pen and paper and started to do some sums re heat loss and insulation ect It really isn't difficult and once you get a hang if it decisions make themselves. 

 

My original plan was a Z shaped house built to Breg insulation standards with demand controlled ventilation, a solid fuel cooker, a woodstove, solar thermal UFH, double glazing. 

 

Gradually everything got eliminated and changed. We built our third design we got planning for. It's a simple rectangular passive house with no solar panels, no central heating, MVHR , 3G, no stoves. 

 

Ultimately the numbers don't lie. 

[SteamyTea]

7 hours ago, Iceverge said:

I sat down with a pen and paper and started to do some sums re heat loss and insulation ect It really isn't difficult and once you get a hang of it

7 hours ago, Iceverge said:

Ultimately the numbers don't lie. 

Wash your mouth out with soap, we all really know that ill informed opinion is the ultimate truth.

[Kelvin]

I’ve eliminated rads upstairs and the wood burning stove for similar reasons. We also eliminated 2 bathrooms and redesigned our plans which reduced the house size by 80m². We’re still putting in PV but I am in two minds about the battery storage.