Hello Everyone

[Grey Sage]

Hello,

After 30 years of burning anthracite in an 1970s vintage central heating system we've decided to decarbonise. We already pay a small fortune to Octopus Energy for guaranteed renewably generated electricity as well as producing some Solar PV. We're looking at air source heat pumps. We're looking at the MCS route, accredited installer, EPC, Professional Heat Loss report & RHI. Signed on here to get unbiased advice. I don't trust the "free surveys" by salesmen. I think that the manufacturers that they recommend are probably the ones which give them the greatest mark-up. 

 

Will post in "other heating systems" with specific questions.

 

The Grey Sage  

[Conor]

Welcome! Admire your principles and best of luck.

[Gus Potter]

Hello Grey Sage.

 

You'll get plenty good info here to enable you to take a view on what is best for you.

 

To get the best out of Build Hub can I suggest as a starting point you provide a bit of info on what you know about the existing construction. For example. The floors .. suspended or solid, wall type / cavities, roof construction, windows and existing levels of insulation. Also if you can give an indication of the floor area of the house and ceiling heights and number of storeys.

 

 

 

 

 

 

[SteamyTea]

Welcome.

 

As Gus says, do a basic heat loss analysis, and if you know how much coal you have been using, and when, the amount of energy that supplies can be estimated.

 

I would be very surprised if Octopus actually supply 100% renewable energy, I don't think they have the generation capacity, more a case of trading with REGOs and double counting their generation capacity.  They have a habit of buying existing generation capacity or partnering with other companies (Tesla being one of them, which boosted their share value).

I am starting to think they are not very moral.

Edited November 9, 2021 by SteamyTea

[Grey Sage]

13 hours ago, Gus Potter said:

Hello Grey Sage.

 

You'll get plenty good info here to enable you to take a view on what is best for you.

 

To get the best out of Build Hub can I suggest as a starting point you provide a bit of info on what you know about the existing construction. For example. The floors .. suspended or solid, wall type / cavities, roof construction, windows and existing levels of insulation. Also if you can give an indication of the floor area of the house and ceiling heights and number of storeys.

 

 

 

 

 

 

Thanks Gus. Should I post here of in Other heating systems. I already have an EPC and a full Heat Loss Report, although the two give very different estimates for both space heating and DHW.

[SteamyTea]

5 minutes ago, Grey Sage said:

Thanks Gus. Should I post here of in Other heating systems. I already have an EPC and a full Heat Loss Report, although the two give very different estimates for both space heating and DHW.

The EPC is a very basic survey.

What was the other report, a full SAP?

[Grey Sage]

13 hours ago, SteamyTea said:

Welcome.

 

As Gus says, do a basic heat loss analysis, and if you know how much coal you have been using, and when, the amount of energy that supplies can be estimated.

 

I would be very surprised if Octopus actually supply 100% renewable energy, I don't think they have the generation capacity, more a case of trading with REGOs and double counting their generation capacity.  They have a habit of buying existing generation capacity or partnering with other companies (Tesla being one of them, which boosted their share value).

I am starting to think they are not very moral.

I currently burn 3.1 tonnes of anthracite, in a season, at £410/tonne. Apparently that's about 12 tonnes of CO2! 

 

I agree that Octopus buy in renewable generation but would like to trust that they are actually selling what they claim. Better than some of the "offset" scams.

[Grey Sage]

Just now, SteamyTea said:

What was the other report, a full SAP?

Yes. It corresponded very closely to my own calculations using the free MCS Excel spreadsheet from their website. He used a program called "Heat Engineer". The one thing that I didn't like about it was the different environmental data which meant that the "design external temperature" was -2.2. I think -3 is the industry standard.

[SteamyTea]

Anthracite is between 26 and 33 MJ/kg.

So around 7.2 to 9.2 kWh/kg.

So you use about 25 MWh/year.

A fair slice of that will be lost to inefficiencies 'up the chimney'.

But say you get 18 MWh/year, with 60% of that used in the 4 or 5 winter months.

That is not an excessive amount of energy.

[epsilonGreedy]

6 minutes ago, Grey Sage said:

I currently burn 3.1 tonnes of anthracite, in a season, at £410/tonne. Apparently that's about 12 tonnes of CO2! 

 

 

I blame those pesky heavy oxygen atoms for those 12 tons.

 

What is your current EPC band or number?

[SteamyTea]

13 minutes ago, Grey Sage said:

agree that Octopus buy in renewable generation but would like to trust that they are actually selling what they claim. Better than some of the "offset" scams

When they 'buy in', there is a hole left to be filled.

It Is better to just use the industry averages for energy intensity.

Or work out the marginal difference when excess generation is brought on line i.e not enough RE, fire up another gas plant, even if it is only supplying 20% of its capacity.

Edited November 10, 2021 by SteamyTea

[Grey Sage]

2 minutes ago, epsilonGreedy said:

EPC band or number

A low D at a score of 75. I'm planning on adding 300mm of loft insulation onto a naked bit of loft to bring my average up to 200mm. The EPC quotes a "saving" of 471 kWh per year but, more to the point, I've been advised that not doing it will disqualify me from the RHI.

[Grey Sage]

Just now, Grey Sage said:

a score of 75.

Oopps. 57

[epsilonGreedy]

4 minutes ago, Grey Sage said:

A low D at a score of 75. I'm planning on adding 300mm of loft insulation onto a naked bit of loft to bring my average up to 200mm. The EPC quotes a "saving" of 471 kWh per year but, 

 

 

Sounds like a no brainer regardless of a government scheme. However this will only nudge your annual kWh figure down by 3% if that, so the underlying question is can an ASHP work effectively and economically in a band D home?

 

One assessment trick mentioned here before is to lower your central heating boiler temp to the typical output temperature of an ASHP and see if the existing radiators can keep the house warm during a cold snap.

[Grey Sage]

4 hours ago, SteamyTea said:

So you use about 25 MWh/year.

That is the figure I've been working with.

75% efficiency gives18,750 kW/8 months. Typically we run the system beginning of September - end of April for all space heating and DHW. Remaining 4 months DHW is heated electrically.

 

We also produce 3000kWh/year of Solar PV but I don't know what proportion of that we use and what is exported

 

[Grey Sage]

4 hours ago, epsilonGreedy said:

One assessment trick mentioned here before is to lower your central heating boiler temp to the typical output temperature of an ASHP and see if the existing radiators can keep the house warm during a cold snap.

Played that game. At a flow temp of 50⁰C I'm planning on replacing 12 radiators to give space heating of 31,313kW/yr.

[SteamyTea]

It is kWh (energy), not kW (power).

The first is how full the shed of coal is, the second is how quickly you empty it with the shovel.

[Grey Sage]

9 hours ago, epsilonGreedy said:

One assessment trick mentioned here before is to lower your central heating boiler temp to the typical output temperature of an ASHP and see if the existing radiators can keep the house warm during a cold snap.

Played that game. At a flow temp of 50⁰C I'm planning on replacing 12 radiators to give space heating of 31,313kWh/yr.

DHW requirement is 6,340kWh/yr but some of that will be provided by solar PV.  We  produce an average of 3000kWh/year. At the moment I don't know what proportion of that we use. I plan to dedicate all of it to DHW either via an immersion or possibly via a Sunamp.