SSE but that's the night rate and doesn't look like they'll be giving it to me when I renew next month. Flogas are doing 20c nightrate at the moment though by the looks of it.
Heat pump and one stop shop
- Thread starter mir2001
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How much gas are you using to heat the place currently? How many units? Do you have a modern efficient boiler or an old one?
Heat pumps systems are slower to react, so you can assume the system would need to be on longer, and if the house is as leaky as you suggest, it might struggle to get up to temperature, costing you a fortune in the process.
Hi Leo, thanks for your reply, over the course of a year we used almost 12,000 kWh of gas. Apart from the leaky front door which will be replaced one way or another this year, I am not sure how leaky the rest of the house might be. I presumed all technical assessments would include such a measurement - I will call the guy who did it and check if it was. I guess I just presumed that a Heat Loss Indicator would include that by default. Another reason I was interested in the one stop shop was that I thought it put some onus on the installer of the external wrap to ensure the BER standard was hit at the end of the job and so ensure standards but maybe that is totally naive. Everyone seems to be very skeptical about the heat pumps but I guess my concern is that if I pour more money into fixing up the gas one pipe system, I may find that I eventually have to scrap gas in 5 years and find more money for a new heating system.
Thanks for all those details. much appreciated - some quick questions - what sort of house did you retrofit - how old and how big? Also, when you say night rate - is that the rate for electricity used between certain hours or is this something different? Cheers
Pinoy adventure
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Having personally installed hundreds of heat pumps this year alone I can say they are excellent in the right environment.
In the wrong environment they are a nightmare for running cost.
The house was built around 2000. 400sqm dormer with cavity walls. Insulation levels were already fairly high when we moved in, so it had a B2 BER. By the time it’s finished we’ll have pumped the rest of the cavity in the walls, increased floor insulation in a few rooms where we installed UFH, all passive wall vents removed and a MVHR system installed, all windows/doors replaced with triple glazed, 16kW heatpump installed, work on airtightness following Mick’s advice (downlighters covered, airtight tapes around floor-to-wall joints etc) and some solar PV. BER will be A2 at that point according to the heatpump assessment we had done.
To Mick’s points above though, I actually think the airtightness work is going to have the biggest impact on comfort in the house, there were huge holes behind some of the skirting that cold air would howl through in the winter. I understand why an airtightness test/assessment is not part of the BER assessment given how many of them need to be conducted to allow house sales etc, but the SEAI not requiring one as part of the heatpump assessment is absolutely crazy. You’re spending maybe €10-20k putting in a heatpump, what’s another few hundred to have the airtightness properly assessed when it is going to have a huge impact on the outcome.
Having said all that, improving the airtightness of your house is unlikely to be much extra work/cost when you’re having so much done anyway. Now that you know you should be doing it, you can just have your contractor factor it in. An assessment before they start might be useful to identify the problem areas and set a baseline to work from.
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There is a myth that Heat Pump can't work in older homes.
A heat pump is just a source of heat. If the system is designed properly it can heat anything (even an uninsulated drafty 1970's house).
The key is to get the heat pump to heat the house at a lower cost than your current heat source. This depends on the cost of the fuel vs the cost of the electricity AND the efficiency of the old system vs the efficiency of the heat pump.
E.g.
Gas Boiler 85% efficient 10c per KWh = 11.76 cent per KWh of heat
Heat Pump 300% efficient 20c per KWh = 6.67 cent per KWh of heat
These are just made up numbers but you get the point. I did some rough calculations that (at a certain price point in time) showed you needed the Heat Pump to be ~260% efficient (COP 2.6) to break even.
In order to get good COP numbers (i.e. high efficiency) from your heat pump you have to run it at low temperatures (i.e. <45oC or better yet 35oC). But in order to heat a large area (or an old uninsulated drafty 1970's house) at low temperatures you need Very BIG radiators.
Of course it makes more sense to 1st upgrade the house because then you need a smaller heat pump and smaller radiators. But it is incorrect to say a heat pump won't work for old houses.
A heat pump is just a source of heat. If the system is designed properly it can heat anything (even an uninsulated drafty 1970's house).
The key is to get the heat pump to heat the house at a lower cost than your current heat source. This depends on the cost of the fuel vs the cost of the electricity AND the efficiency of the old system vs the efficiency of the heat pump.
E.g.
Gas Boiler 85% efficient 10c per KWh = 11.76 cent per KWh of heat
Heat Pump 300% efficient 20c per KWh = 6.67 cent per KWh of heat
These are just made up numbers but you get the point. I did some rough calculations that (at a certain price point in time) showed you needed the Heat Pump to be ~260% efficient (COP 2.6) to break even.
In order to get good COP numbers (i.e. high efficiency) from your heat pump you have to run it at low temperatures (i.e. <45oC or better yet 35oC). But in order to heat a large area (or an old uninsulated drafty 1970's house) at low temperatures you need Very BIG radiators.
Of course it makes more sense to 1st upgrade the house because then you need a smaller heat pump and smaller radiators. But it is incorrect to say a heat pump won't work for old houses.
The SEAI numbers are a reasonable guide for heat energy costs and they now include heat pumps, see the most recent April data.
Even factoring in heat pump COP, gas is still cheaper.
Thanks, your experience is really helpful. I’ll ring the assessors tomorrow morning and find out more about the air tightness element, it is crazy if this hasn’t been included. I did notice there is s section in the grant application for airtightness but that is blank. I agree with you about getting that work done as part of the package but the problem for me is that the expenditure is already a lot for me so I can’t afford to keep spending more, even when it’s a small amount.
Those figures are very interesting so thanks for that, my concern is that I will do the upgrades and then find it’s not enough but at that point there’ll be no going back.
Pretty close. There will also be some loss from the pipework that isn't accounted for in the boiler efficiency rating, varying with the seasons (ambient temperature). They state the methodology they use to calculate that is on their site but I haven't been able to find it. If your pipework is all insulated you could assume that is low.
For heat pumps they maintain a database where you can look up the Seasonal Performance Factor.
Oh, the delivered cost is what I was looking at, but I should have been looking in the other columns!! D'oh!
Yes, so just to clarify the Data that Leo linked to shows that a heatpump is cheaper than gas.
A 90% efficient Gas boiler would cost 12.8 to 20.3 cent per KWh of heat
A Heat Pump with COP of 3 would cost 10.1 to 17.5 cent per KWh of heat
Firstly, sorry for not getting back to this earlier - one of those weeks!
I have to admit those figures were not clear at all to me so thanks @AJAM @Zenith63 and @Leo for looking into all this in such detail and clarifying, very much appreciated.
Just have a few followup questions
1. COP factor, I presume this is the same for everyone but varies according to the temperature outside?
2. Presuming you had a well insulated, airtight house, I take it that a heat pump would be cheaper to run than a gas boiler once you got the initial temperature in the house to an acceptable level?
3. Would you expect that it would take much extra work/much extra disruption if, after adding external insulation and new windows and doors, airtightness turned out to be an issue?
Thanks
The devil is in the detail was never more apt than for the questions you are asking... presume nothing!
1. While the external temperature definitely impacts the COP, the design and install can have a much bigger impact, i.e. either a poorly designed or installed heat pump (size, distribution system, control etc) can result in a horrendous COP.
2. You have to do the sums and it depends on the unit price for each energy source combined with the actual system efficiency but generally you should expect that a hp is cheaper to run.
3. Addressing air tightness / ventilation should be central to any fabric upgrade, so thinking about it afterwards is not a great idea and, depending on a number of factors such as house type / layout / build method etc etc, could add significant extra expense / disruption even to the point of undoing some of the recent upgrade works.
Thanks @Micks'r
I guess I need to ensure the one stop shop company are well regarded - thing is the one I am talking to are well regarded in the housing estate but nobody has ever had a heat pump installed by them so difficult to assess this aspect.
It would seem I need to get an air tightness assessment carried out prior to any works taking place then. I still have to get back to the company that did the technical assessment to make sure this wasn't included but there is no mention in the report so I presume it wasn't.
I certainly cannot afford to start undoing upgrade work when the upgrades themselves will be a big stretch for me financially.
If you were home at the time you’d know if it was done, they’d be sealing up all your vents then sealing the front door and using a big blower to try and pressurise the house. It’s not subtle
. But if it was the standard SEAI assessment then it would not have been done.If you were home at the time you’d know if it was done, they’d be sealing up all your vents then sealing the front door and using a big blower to try and pressurise the house. It’s not subtle
I'm almost certain that wasn't done - the only preparation that was made was covering any mirrors.