Looking at replacing Electric boiler for combi boiler
- Thread starter Tryale
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1. A typical gas combination uses between 24 and 30 kw of power all the time it is heating the water. This allows it to (typically) provide hot water at between 11 and 14 litres per minute, the water being heated to around 65 degrees.
2. You need roughly 4 amps of electricity per kw (UK) so you'd need 96 amps to provide 24kw of "instant" heating. This is not feasible in the average home.
3. Even if you could achieve it, any savings would depend on pattern of use, and whether running off cold water from the hot pipes is less wasteful than losing heat from a cylinder (plus the associated run off).
4. Even if were feasible, and there was a saving, it would probably be many years before the change paid for itself.
2. You need roughly 4 amps of electricity per kw (UK) so you'd need 96 amps to provide 24kw of "instant" heating. This is not feasible in the average home.
3. Even if you could achieve it, any savings would depend on pattern of use, and whether running off cold water from the hot pipes is less wasteful than losing heat from a cylinder (plus the associated run off).
4. Even if were feasible, and there was a saving, it would probably be many years before the change paid for itself.
Thank you for coming back. Unfortunately there is no gas to the house . I can only get electric. The quote I've had is just over £4000 for the combi boiler . Would you or anyone be able to give any rough idea of what sort of saving per year I could make with if I were to go for this.
I'm afraid you've missed the point in the above post. The comparison with a gas combi boiler was to show the large amount of power you require to provide instantaneous hot water demand, at a decent flow rate. This will be true for electric, or gas boilers.
With a highly insulated hot water tank, the relatively small immersion element can provide all the hot water you want, relatively efficiently.
Just to break even on the cost of the boiler, over its lifetime, you would have to make savings of at least £30/month.
I may be wrong, but this seems a big outlay for little gain.
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Forgive me I see your point now, thank you.
The savings are zero.
If you are heating with electricity, then the cost is based entirely on how much hot water is used and how much heat you want in your house.
For hot water, whether it's heated and stored or attempted to be heated on demand changes almost nothing. There are some losses from hot water stored in a cylinder, but with a modern cylinder those will amount to pennies per day. Most losses for hot water are from the pipework, which is the same for a combi or hot water cylinder.
For space heating via radiators and whatever there is no difference at all.
If you only have electricity and want to reduce the cost by a meaningful amount then there are only a few realistic choices:
1 - Heat the house less, which means installing insulation or reducing the interior temperature.
2 - Find a much cheaper source of electricity such as a cheap overnight tariff or solar panels
3 - Use a heatpump for the space heating instead of a direct electric element.
1 has a modest cost and is almost certainly worthwhile.
2 may incur a higher price during peak hours so you must determine the total overall cost, not just whether it's cheaper at certain times
3 has a very high initial outlay.
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Have you considered using oil or LPG for space heating? Don't know about LPG rates in UK but it would be cheaper than electricity for sure.
Thank you. Though I don't believe that LPG would be possible due to not having the land to place the bulk LPG container
That would involve an entirely new system and the £1000s would be better spent on a heatpump.
That would be an issue I just own a small bit of patio unless I can fix it to a wall. Also do you not need unfloor heating installed for this ? Has anyone here had a heat pump installed ?
You don't need UFH just oversized radiators. I think most require some outside space. Get some quotes?. Octopus are coming in fairly cheap.
It needs a proper heat survey completed. Do you have a well insulated house?
You could use air to air heat pumps (air conditioning) and use the immersion for hot water
No.
A heatpump could be used with underfloor heating.
Or it could be used with radiators
Or if neither of those are wanted, air-air systems are available which don't use radiators or underfloor heating.
Ultimately it's a box which outputs hot air or hot water.
They can be floor standing, or wall mounted.
Plenty of options are available.
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