Economics of replacing storage heaters with ASHP?

ed110220

Hi all, does anyone have any experience (or just thoughts) on replacing storage heaters (on economy 7) with ASHP?

I'm trying to put together a case for my sister to change her ancient storage heaters which are rather expensive to run and suffer the old problem of having almost run out of heat by the evening when you want it most. She lives in a park home so it's pretty small (one bedroom) and at the moment is heated by a storage heater in the kitchen, one in the bedroom and an electric fire (non-storage) in the living room. I'm thinking that two ASHPs, one in the living room and one in the bedroom, would be sufficient.

This is a house of a similar (not identical) floorplan:-



My thinking is that the higher COP of the ASHP and the fact that it can be run only when needed will much more than compensate for the higher unit cost of electricity.

Reed_Richards

When I looked for an ASHP sized for a single room all I could find was air conditioning units. These mostly use heat pumps and can mostly be run in heating as well as cooling mode. So I think they are the same thing under another name. Have you actually found an ASHP marketed as an ASHP?

mmmmikey

Hi - my bungalow is mainly heated with E7 storage heaters but I also have an ASHP in the bedroom and I'm a big fan of both. A couple of questions, before answering yours, if I may.....


1. How well insulated is the home? Is it an older "freezing in the winter and like an oven in the summer" place or does it handle the extremes fairly well?
2. Is your sister at home much during the day?


Sorry for answering your question with a question - it just saves a lengthy "if this then that" kind of answer

mmmmikey

Reed_Richards wrote: »

When I looked for an ASHP sized for a single room all I could find was air conditioning units. These mostly use heat pumps and can mostly be run in heating as well as cooling mode. So I think they are the same thing under another name. Have you actually found an ASHP marketed as an ASHP?

ASHP for single rooms are also known as air to air heat pumps and pretty much the same thing as aircon units. Most of the discussion on this forum refer to this type of unit. In effect, they're just aircon units with a reverse switch. Here's an example of an inexpensive unit that works as well for heating as it does for cooling (I know because I've got one)


https://www.cooleasy.co.uk/categories/easy-fit-air-conditioning/high-wall/2-6kw-midea-blanc-wall-mounted-system.html

ed110220

mmmmikey wrote: »

Hi - my bungalow is mainly heated with E7 storage heaters but I also have an ASHP in the bedroom and I'm a big fan of both. A couple of questions, before answering yours, if I may.....


1. How well insulated is the home? Is it an older "freezing in the winter and like an oven in the summer" place or does it handle the extremes fairly well?
2. Is your sister at home much during the day?


Sorry for answering your question with a question - it just saves a lengthy "if this then that" kind of answer

Hi, it's relatively old, I'd guess maybe 35 or 40 years old. The walls are extremely flimsy a wooden frame about 50mm thick with plywood on.the outside, some sort or hardboard (replaced with plasterboard where shes redecorated) on the inside and rockwool in between. It gets cold in winter and hot in summer. I've suggested external wall insulation to help with this.

She's usually at work or out in the day.

Martyn1981

ed110220 wrote: »

Hi, it's relatively old, I'd guess maybe 35 or 40 years old. The walls are extremely flimsy a wooden frame about 50mm thick with plywood on.the outside, some sort or hardboard (replaced with plasterboard where shes redecorated) on the inside and rockwool in between. It gets cold in winter and hot in summer. I've suggested external wall insulation to help with this.

She's usually at work or out in the day.

If she gets EWI then everything will change considerably, but, since it's already leccy heated I'd suggest the issue remains the same, so .... to ASHP or not.

It seems like a pretty simple decision to me when heating the house at night from E7 with the ASHP's, but the issue then is evening warmth with the ASHP at standard rates, but if the storage heaters are already struggling, and a leccy heater is being used anyway, then it swings back in favour of the ASHP's again.

I think the higher efficiency of the ASHP's (making up for daytime import rates), and their flexibility, and the A/C element, all for perhaps £2k, looks like a good choice. Perhaps leave the storage heaters in place for a 'just in case' boost during exceptional circumstances ...... though EWI will sort that.

Sorry, I'm repeating most of what you said, as I think out loud, but what you suggest does make sense to me.

JKenH

ed110220 wrote: »

Hi, it's relatively old, I'd guess maybe 35 or 40 years old. The walls are extremely flimsy a wooden frame about 50mm thick with plywood on.the outside, some sort or hardboard (replaced with plasterboard where shes redecorated) on the inside and rockwool in between. It gets cold in winter and hot in summer. I've suggested external wall insulation to help with this.

She's usually at work or out in the day.

You might think I’m stating the obvious but given the construction, you would probably have to undertake some reinforcement to take the weight of the internal unit and ground mount the external unit. Will vibration be transmitted through the walls or might the panelling act as a soundboard?

Reed_Richards

The biggest financial benefit will be to replace that electric heater in the living room with an ASHP. Perhaps you could do that first and see how it goes? Dwellings in a park home tend to be quite close together so you might get complaints from the neighbours if the fans make noise - another reason to try just the one first.

JKenH

Reed_Richards wrote: »

The biggest financial benefit will be to replace that electric heater in the living room with an ASHP. Perhaps you could do that first and see how it goes? Dwellings in a park home tend to be quite close together so you might get complaints from the neighbours if the fans make noise - another reason to try just the one first.

I imagine (for reasons like this) your sister will need to check with the owners of the park if external mods such as an ASHP are allowed.

mmmmikey

Hi I agree with all the above comments, and my view is that you'll probably be better off with ASHPs than the storage heaters. I'm a big fan of E7 storage heaters and they've helped me halve my energy bill, but they don't work well in less insulated properties because of the heat loss during the day. The loss that matters is the loss from the inside from the outside, not from the heater to the room. If you're in during the day most of the time this is less of an issue because you can use the heat. Definitely worth considering the noise implications of the outside unit.

ed110220

Are the fans of the external units really that noisy? Hadn't thought about that being a problem. Not sure if they would count as changing the external appearance of the house, especially as they wouldn't be visible from the front but worth checking with the council who own the site.