storage heaters/electric central heating or gas?
Comments
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I use a thermal store system heated by an electric heater. I was advised that the water in the store should be maintained at around 80 degrees centigrade. Can a ASHP bring water to that temperature?0
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I use a thermal store system heated by an electric heater. I was advised that the water in the store should be maintained at around 80 degrees centigrade. Can a ASHP bring water to that temperature?
No you can't; you'd have to boost it with electric to get to that temperature as the ASHP will only get to around 55deg (although the cost of doing this is going to be less than heating purely by electric). However, I believe that you only need to get to that temperature for two reasons...firstly, for destroying legionaires disease IIRC you need to heat it to above 60degC once a week, although i'm not sure how relevant this is for indirect systems where you don't actually come into contact with the water in the store.
Secondly, normal radiators are designed to be run at around 80degC, so if you created a system based on 55deg water, you would need to oversize the radiators. How much to oversize is the problem, with claims from 20% to 100% to provide the same level of comfort. Alternatively, you can use underfloor heating that is designed to operate at around 35deg (which is the preferred solution).
The system I'm looking at is the Gledhill Boilermate HP-DEM combined with a Mitsubishi heat pump (sold as a package direct from Gledhill). The HP is as follows:
http://www.mitsubishi-aircon.co.uk/default.asp?url=http://www.mitsubishi-aircon.co.uk/mitsubishi_electric.asp?id=168143
and the Boilermate is on the Gledhill.net website under alternative energies:
http://www.gledhill.net/water-storage/ws-index.htm0 -
I also wasn't aware that the Mitsubishi ASHP had the facility to connect its output to an air to water heat pump(a convertor) I would be interested in how this works(and how efficient it is) have you any technical details?
What is the maximum temperature of water that your ASHP/converter will provide?
IT is a combined ASHP and convertor so just has the flow and return connections for connecting to an [indirect] thermal store. See link in post above that leads to the brochure.
The maximum temperature is 55deg OTTOMH, but can obviously be boosted by electric in the thermal store if you so wished.
The other achiles heal is that the efficiency of the heat pump drops as the outside temperature drops, so isn't as good when you most need it to be. On the plus side, in the summer, the efficiency increases, up to around 4:1, so on E10 you could be heating your hot water at a cost of 5p/4 per kwh = 1.25p/kwh...half the price of gas.0 -
In my neck of the woods you can get grants for ground, air or water source heat pump systems, you might get info from the Energy Saving Trust0
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In my neck of the woods you can get grants for ground, air or water source heat pump systems, you might get info from the Energy Saving Trust
Yes, in our neck of the woods, we can get grants for ground only
Due to the layout of our land, GSHP would be so expensive to do that I don't think that you'd ever see the payback unfortunately So ASHPs seem to be a good compromise for us. 0 -
samtheman1k wrote: »IT is a combined ASHP and convertor so just has the flow and return connections for connecting to an [indirect] thermal store. See link in post above that leads to the brochure.
The maximum temperature is 55deg OTTOMH, but can obviously be boosted by electric in the thermal store if you so wished.
The other achiles heal is that the efficiency of the heat pump drops as the outside temperature drops, so isn't as good when you most need it to be. On the plus side, in the summer, the efficiency increases, up to around 4:1, so on E10 you could be heating your hot water at a cost of 5p/4 per kwh = 1.25p/kwh...half the price of gas.
Thanks - seems like it could be good news.
It will be great to see your data after a year.
As an aside 5p/kWh seems to be quite a lot for E10.
I appreciate that prices vary by region but is that the cheapest?
I wonder if E7 might not be an option? With all prices on BG Click 4 under 3p/kWh(incl VAT and before discounts) might that not be an option?
I suppose that until you get some data on which to make calculations it will be difficult to judge. i.e. How much you use in the 'extra' 3 hours judged against paying an extra 2+p for 7 hours.0 -
As an aside 5p/kWh seems to be quite a lot for E10.
I appreciate that prices vary by region but is that the cheapest?
I wonder if E7 might not be an option? With all prices on BG Click 4 under 3p/kWh(incl VAT and before discounts) might that not be an option?
I suppose that until you get some data on which to make calculations it will be difficult to judge. i.e. How much you use in the 'extra' 3 hours judged against paying an extra 2+p for 7 hours.
We are in the SE and have only found one company offering E10, and their E10 rate is 5.08p inc VAT but excluding discounts. We were on Scottish E7 where it was about 3.5p ex VAT. I guess it comes down to the amount of time it will be used during the on/off peak hours, which I haven't worked out yet with this system.
The boilermate doens't really hold that much hot water, 180L, which certainly isn't enough to heat a house for a day + hot water, so would definitely need to be topped up which is why I was looking at E10. But you're right, it's all a bit of an unknown at the moment and with very little impartial data on how well ASHPs run for central heating it's a bit difficult to know without making [intelligent] guessing!0 -
samtheman1k wrote: »We are in the SE and have only found one company offering E10, and their E10 rate is 5.08p inc VAT
Somebody on here, forget who but they worked for a Utility company, said that all companies must provide E10; however some are reluctant to do so. Might be worth a query with Energywatch to see if that is true.
Rather than pay 5+p for E10, plus a premium for electricity during the other 14 hours, a flat rate of 7+p 24/7 could be an option??? The advantage being that the COP will be higher during the day when it is warmer.
Decisions, Decisions!!
At least after monitoring your consumption for a while you will have some data on which to base your decision on the best tariff.0 -
when wind turbine prices get more realistic you could run the pump from that, their low power output would be multiplied by the heat pump.0
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Somebody on here, forget who but they worked for a Utility company, said that all companies must provide E10; however some are reluctant to do so. Might be worth a query with Energywatch to see if that is true.
OK, let me rephrase that, there is only one supplier who I've got to agree to install E10 (i.e. admit that they can!).Rather than pay 5+p for E10, plus a premium for electricity during the other 14 hours, a flat rate of 7+p 24/7 could be an option??? The advantage being that the COP will be higher during the day when it is warmer.
Yes, that is probably what I'm going to start on and see how it goes. It really is impossible to work out which tariff would be best without knowing what the consumption is going to be like!0
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