60s flat renovation - what's the best way to go?

[skiberd]

Hi all, bit of a blank slate question here... I've recently purchased a 1960s former local authority flat in London that needs complete renovation. I'm a bit of an eco-zealot (we all are down here) and into new tech so was wondering what's the best way to heat it and for hot waters.

 

I don't have the heatloss figures but it's 1 bed and 42 sqm with flats above, below and either side with thick concrete floors, ceilings and properly solid walls. It has windows facing east and west so gets decent sunlight all day and OK double glazing. It feels fairly well insulated, but I am coming from a wonky Victorian thing. I'll also be fitting cork flooring.

 

I'm binning the bath so will only need hot water for a shower and two taps, and there are currently only 4 radiators (2 large, 2 tiny). Piping is all external so upgrading this will be a doddle.

 

I had originally thought about getting rid of the whole wet system and going with 'smart' IR ceiling heaters and a Mixergy tank set to the Octopus tarriff but this is about £5K and I've read a lot of conflicting things about how much it will cost to run.

 

Another options (assuming I don't get permission for an external fan unit) is the GS200 from Ground Sun with everything internal and in one unit (there are two big vents in the external wall where the old boiler is). About the same price, does both heating and water plus should be more efficient.

 

The other option is swap out the ancient combi something modern for less than half the price and eat away my liberal carbon guilt with the savings.

 

Fully open to ideas. Pretty mad there isn't more solid advice out there as there will be 000s of people in a similar position over the next few years.

 

Thanks!

[SteamyTea]

20 minutes ago, skiberd said:

eat away my liberal carbon guilt with the savings.

Invest in a wind or solar farm.

 

[joth]

> "assuming I don't get permission for an external fan unit"

Get the application in for the external ASHP unit, knowing where you stand with that will help other decisions a lot.

 

> "Mixergy tank set to the Octopus tarriff but this is about £5K"

Remember that the octopus tariff may not last forever so you want to future proof against prices changes. That said without a bath and in a 1b flat overall DHW should be pretty low. Personally I'd ditch the complexity of the Mixergy and just go for a well insulated conventional UVC - ideally ASHP ready.

 

>GS200 from Ground Sun

Not familiar with this but it does seem a legit alternative.  Obv. puts a bit more noise inside the building, but so long as you can live with that on paper it seems the tool for the job. Stated COP of 3.5 is fine. It only delivers heating water up to 40ºC so you'll definitely need oversized of fan assisted rads. Again if you can time running it so noise isn't an issue, fan-assisted probably works best.

 

 

 

 

 

 

[ReedRichards]

20 hours ago, skiberd said:

I had originally thought about getting rid of the whole wet system and going with 'smart' IR ceiling heaters

 

I don't think IR ceiling heaters are remotely smart.  Now I did invent an IR heater attached to a drone so it would fly around and always keep 1 m away from me.  That way I got the most benefit from the heat as I moved around the building.  The drone noise was a bit of an issue but the main problem was that it kept strangling me with the flex.   My next iteration will have an array of tracks on the ceiling and will work in the manner of an electric tram. 

[SteamyTea]

11 minutes ago, ReedRichards said:

invent

Or dream?

11 minutes ago, ReedRichards said:

My next iteration will have an array of tracks on the ceiling and will work in the manner of an electric tram. 

Now that is an idea worth pursuing.  Flashing website, nice write up by a recent graduate in Marketing and PR.

Get millionaire investors on board, then retire.  No need to actually sell any hardware.

Seems to have worked for many companies that are going to save the planet.

Edited July 6, 2022 by SteamyTea

[skiberd]

Thanks everyone - from the spec (attached) I've been sent the GS200 has a COP of 3.16 and heats water up to 60C so hopefully I won't need fan assisted rads (any advice on radiators paired with an ASHP would be grand!) It supposedly runs at 49dB which I've just done a v unprecise experiment with using a decibel app and a video of a fan which seems fine - it's in the corner of the flat away from the bedroom, is in London and I have tinnitus anyway.

 

Another total beginner question - is figuring out whether it'll pay for itself/be at least comparable versus a combi boiler as simple as multiplying the COP by my gas tariff? Plus I guess there's all the fun of trying to predict how much electricity and gas will go up over the next year or so, but you'd hope the UK makes itself less reliant on gas for a whole bunch of reasons

 

 

GS200 brochure with technical data.pdf

[SteamyTea]

2 hours ago, skiberd said:

heats water up to 60C

Is that purely heat pump driven, or does it use the built in resistance heater as well?  i.e. it has a CoP of 1 at 60°C.

[joth]

5 hours ago, SteamyTea said:

Is that purely heat pump driven, or does it use the built in resistance heater as well?  i.e. it has a CoP of 1 at 60°C.

 

Good question.

 

The spec sheet claims COP of 3.16 is for 54.4 °C "reference temperature", which if true is extremely good. Doesn't mention what outdoor temperature though 

 

The image appears to show 2 immersion heaters, and the spec had a strange statement:

"Energy output includes built in Erods"

 

Erods?

 

I'm skeptical what the real world performance would be, but open to the idea.

[ReedRichards]

Quote

• E-rods built in for 100% backup

Must be some form of immersion heater.

 

12 hours ago, skiberd said:

...the GS200 has a COP of 3.16 and heats water up to 60C

But not both at the same time.  My ASHP heats water up to 60 C but only by taking control of my immersion heater for the final 5 C or so.

[ProDave]

Why do you want to heat your DHW to 60 degrees?  Plenty of us in here heat out DHW to 48 degrees with an ASHP and it is plenty hot enough.  Because you will dilute the hot water with less cold in use, you do need to consider a larger tank, mine is 300 litres.

 

48 degrees was chosen by me by experiment as the hottest I could just about hold my hands under if  filled the kitchen sink just with hot water.  Why would you want it hotter than that?

[JohnMo]

I would really investigate the insulation and airtightness, get them all to a very high standard.  That size of flat will only need next to no heat then.  The heating requirements should so low that the house will take the excess heat from the flats connected to it.  You should be getting your heating requirements down to below a 1kW for the whole flat.

 

Install dMVHR for ventilation.

 

Electric UFH heating in bathroom,with electric towel rad, on a timer.  Simple panel heater or storage heater in the living space, immersion heater on suitable tariff for hot water, or air source Hot water tank.  But take air outside, not inside.

 

[ProDave]

5 minutes ago, JohnMo said:

Install dMVHR for ventilation.

How do you do that in a flat where you probably have no access to the inter floor space above the flat?

[JohnMo]

dMEV goes in a hole made in a wall same as a normal vent fan, but has built in supply and extract with heat recovery.  No need to access to any inter floor spaces as there are no ducts.

[joth]

4 hours ago, ProDave said:

Why do you want to heat your DHW to 60 degrees? 

The 60° comment was for the CH circuit, to avoid needing fan assisted rads.

I agree with the other comments that it's by no means a given CH and rads are needed at all.

Edited July 7, 2022 by joth

[skiberd]

All the acronyms here! It's pretty annoying the government grant doesn't cover the GS200 - if I did have outdoor space I could get a £10k system for the same price. With the low expected demand I'm leaning towards an efficient new combi (about £1800 for the Vitodens 050-W fitted) vs £5k+ for the ASHP route, unless there is a chance it would pay for itself.

 

I'll wait to see what the Ground Sun engineers say as the unit is usually for new builds and not retrofitting. Maybe in a few years the tech will be a bit more accessible as it's a definite gap in the market...