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Air sourced Hot Water Cylinders


Stevo129

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Hi

Has anyone got a Air Sourced Hot Water Cylinder. Various manufacturers are making outrageous claims that these cylinders cost pennies to run. What is the real truth. If anyone has had one for a while I would really love to know what they cost to run in the real world.

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Simple truth is to heat a set volume of water takes the same amount of energy plus a bit for heating coil efficiency loss)  Heat loss will depend on how well insulated the cylinder is and how well the pipes coming of the cylinder are insulated.

 

Some manufacturer will make it possible to heat a small part of the cylinder, so only a small percentage of the cylinder is heated, cutting down heating cost, but also water available to use.  Great if you live alone and sometimes have a house full.  But may not be much use for the normal family.

 

Big surface area coil (more efficient and quicker reheat time) and thick insulation is best.  Sized to suit your circumstances.

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I have a small (4KW) ASHP that heats my DHW tank (and UFH when it’s needed fir just a couple of months). Works very well, cop of about 4, no mains gas available (so no gas standing order). Yes heat loss is down to insulation but that loss is into the house anyway! So not always a “loss“.

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Exhaust Source Heat Pump is what you're after. 

 

Some cheapo Chinesium ones. No reason to believe they don't work. 

 

Some more expensive ones from known brands. Panasonic etc .  @Thedreamer has a Joule and likes it AFAIK. 

 

Beware the heat needs to come from somewhere, usually inside if that's where the air is exhausted from. . Your space heating may increase during winter (depending on current ventilation strategy). 

 

 

 

 

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We have been using an exhaust air source heat pump since June 2020 and I am very happy with it.

 

Cheap capital cost, cheap running cost!

 

We use it just for domestic hot water for a family of four. It has a back-up immersion heater but we have never used that.

 

It works well for us, because we don't need space heating due to having reasonable levels of insulation, good solar gains and a centrally placed wood stove for winter evening heating. The majority of our wood comes from wind blown trees and sticks which I collect during the year.

 

I have ducts set-up to our ensuite, bathroom and utility. You get a much better average COP then an external air source heat pump as it's always extracting heat at room temperature. 

 

I was worried in the winter that we would lose heat into the system. This has not been issue for us, as the 'free' heating from the stove replaces any reduction in heat loss.

 

You can buy the mini air source heat pump as a separate unit, but most have this integrated with the cylinder so make sure you buy a good quality cylinder. Some of the cheaper ones require regularly changes of anodes, this can depend on your water you have in your area.

 

I store my tank in a cupboard in the utility room, no noise issues.

 

I have never recorded how much electricity the tank uses, but all our domestic electricity for a family of four, averages at 10 units a day over the course of the year. I have no PV.

 

If the £400 rebate goes ahead, my electricity bill from October to March will be zero.

 

 

 

 

 

 

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13 hours ago, Thedreamer said:

You can buy the mini air source heat pump as a separate unit

What make is that, do you have a link.

 

13 hours ago, Thedreamer said:

If the £400 rebate goes ahead, my electricity bill from October to March will be zero.

Trying to make my annual bill zero, used under 2 MWh so far this year.

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42 minutes ago, Marvin said:

Yeah, accept for the daily charge and VAT......

Yes.

57.86p/day standing charge.  £211.19/year.

To help bail out all those skinflints that swapped supplier to get a good deal.  A good deal that I am paying for.

 

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