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Armature looking for advice hot water options


Calw

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Hey 

 

I am looking at cutting my electricity usage 

 

Our 4 bed detached is currently using around 6800kw per year 

Electric hot water (old skool immersion)

Electric cooking (4 ring hob double oven)

Electric heating (never turned on)

 

No gas in the village

 

Since we have installed a smart meter we have found that hot water accounts for about 2/3rd of our electricity usage

 

We have a 200l immersion tank it uses on average 10kw in the summer days and 12 - 13kw in the winter days just to heat water... 

 

On the worst days we have 1 shower and 1 bath that's about 10kw a day on best days where it only takes about 6kw a day that's 2 or 3 showers.

 

So my options are 

 

Install a new all in 1 hybrid Air source water heater

 

Install a new thermodynamic water heating system 

 

I did toy with a back boiler to our stove but that means I would need to run my wood burner in the summer months to get hot water not ideal

 

Would anyone have advice

 

 

 

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In order of preference:

 

Insulate the DHW tank, check if there are are there forever hot pipes "thermosyphoning" your heat away?

shorter showers:-)

PV + diverter

Octopus Go / E7

AROstor or similar tank with inbuilt heatpump

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9 hours ago, JohnMo said:

Are you E7 or similar?

No not e7, at the time we moved in we moved off e7 as our energy use was estimated to be 50/50 water everything else and the best deal we could get was 7p pkw off peak and 19p pkw on peak. And we have an energy supplier offering us 12.4p pkw 24/7 so it made more sense

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9 hours ago, Simplysimon said:

shower/bathe every 3rd day 🙄

Thanks for that useful suggestion, kind of hard when you have a physical dirty job and a 3yo that likes to get dirty 

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9 hours ago, RobLe said:

In order of preference:

 

Insulate the DHW tank, check if there are are there forever hot pipes "thermosyphoning" your heat away?

shorter showers:-)

PV + diverter

Octopus Go / E7

AROstor or similar tank with inbuilt heatpump

The first things I did when we moved in back in 2016 was double jacket the boiler lower the heating temp from 75 to 65 and insulate the loft space to 300mm

 

The arostor, edel options are the ones I am looking at now. It was suggested rather than one of those I look at a thermodynamic panel system. But there is even less information about them in the UK than the AIO heatpump options.

 

Loads of American reviews about the AIO systems but it's harder to translate that to how they would perform here.

 

The arostor and edel both have COP ratings of around 3 which would in theory cut my bill for heating water by 2/3rds. 

 

The AIO option could be ducted from my living room (which in winter has the 5kw stove on 24/7 giving it warmer air to use and I could plumb the exhaust outside meaning I shouldn't see a large cooling effect from the AIO. The only issue there is where my existing tank is its right in the middle of the house and the AIO options are slightly noisy (I would combat that buy running during the day instead of at night)

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10 hours ago, Calw said:

Our 4 bed detached is currently using around 6800kw per year 

That is not excessive.

Your DHW usages seems very reasonable, how many in the house?

Space heating is the real challenge, so realistically an ASHP is the way to go.  That means getting the building to a better thermal specification.

You have 4 months to improve airtightness, insulation and general maintenance.  Then take a financial hit on this winters electrical usage, but record usage (get an energy data logger).

It is better to spend a £1000 on one winter's usage than an extra £5000 on an incorrectly sized ASHP.

 

Stored hot water usage is really down to three things, the same three things that affect a house.  Reduce losses, don't overheat and only heat what is needed.

There is no need to store water greater than 48°C, this reduces losses right away, add extra insulation around the cylinder (fill the airing cupboard up with it), and reduce usage if you can, so shorter showers, less baths.

 

Economy 7, or one of the derivatives is an alternative, along with storage heaters.  This will require extra wiring, which will be as messy as plumbing, and like a radiator system, you end up with 'boxes' in the rooms.  Modern storage heaters are pretty good, they take a bit of getting used to, but work as well as any other system.

 

Main thing is to reduce losses, don't be afraid to post up dimensions/sketches of the house.

 

I am 'all electric' and my current daily usage, over the last 2 full weeks, has been 3.5 kWh/day.  DHW is usage (with a bit of washing machine use) is 2.8 kWh/day.  There is just me in the house.

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11 hours ago, Calw said:

We have a 200l immersion tank it uses on average 10kw in the summer days and 12 - 13kw in the winter days just to heat water... 

For eight to nine months of the year we heat our hot water tank with PV plus diverter and solar thermal.

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4 hours ago, JohnMo said:

You don't really want to sucking all the heat out of the living space.  You need to do from wet rooms, this will also assist moving some air through the house

Good advice the reason I was considering that option was we only use the 5kw stove as our only source of heat in winter, the main room can hit

24c but normally around 22c where rest of the house would be around 17c so I thought having the higher temp input would aid cop

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3 hours ago, SteamyTea said:

That is not excessive.

Your DHW usages seems very reasonable, how many in the house?

3 (2 adults and a toddler)

3 hours ago, SteamyTea said:

Space heating is the real challenge, so realistically an ASHP is the way to go.  That means getting the building to a better thermal specification.

You have 4 months to improve airtightness, insulation and general maintenance.  Then take a financial hit on this winters electrical usage, but record usage (get an energy data logger).

It is better to spend a £1000 on one winter's usage than an extra £5000 on an incorrectly sized ASHP.

Not looking to have heating in this equation as our 5kw multi fuel stove does enough of the heating 

(Get free wood and top it off with some coal for a overnight burn so it's not too bad)

3 hours ago, SteamyTea said:

 

Stored hot water usage is really down to three things, the same three things that affect a house.  Reduce losses, don't overheat and only heat what is needed.

There is no need to store water greater than 48°C, this reduces losses right away, add extra insulation around the cylinder (fill the airing cupboard up with it), and reduce usage if you can, so shorter showers, less baths.

 

Economy 7, or one of the derivatives is an alternative, along with storage heaters.  This will require extra wiring, which will be as messy as plumbing, and like a radiator system, you end up with 'boxes' in the rooms.  Modern storage heaters are pretty good, they take a bit of getting used to, but work as well as any other system.

House used to have storage heaters so all the wiring is already there

3 hours ago, SteamyTea said:

Main thing is to reduce losses, don't be afraid to post up dimensions/sketches of the house.

 

I am 'all electric' and my current daily usage, over the last 2 full weeks, has been 3.5 kWh/day.  DHW is usage (with a bit of washing machine use) is 2.8 kWh/day.  There is just me in the house.

So currently around depending on season

 

18kw - 24kw per day usage total

With DHW accounting for between 11kw - 14kw of the 18kw to 24kw total....

 

Edited by Calw
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1 hour ago, Calw said:

With DHW accounting for between 11kw - 14kw of the 18kw to 24kw total....

Start looking at parasitic loads i.e. old gear on standby, most new stuff is pretty low these days.

1 hour ago, Calw said:

Not looking to have heating in this equation as our 5kw multi fuel stove does enough of the heating 

(Get free wood and top it off with some coal for a overnight burn so it's not too bad)

You are aware of the health risks associated with the poorer internal air quality of timber and coal burning?

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16 hours ago, Calw said:

Hey 

 

I am looking at cutting my electricity usage 

 

Our 4 bed detached is currently using around 6800kw per year 

Electric hot water (old skool immersion)

Electric cooking (4 ring hob double oven)

Electric heating (never turned on)

 

No gas in the village

 

Since we have installed a smart meter we have found that hot water accounts for about 2/3rd of our electricity usage

 

We have a 200l immersion tank it uses on average 10kw in the summer days and 12 - 13kw in the winter days just to heat water... 

 

On the worst days we have 1 shower and 1 bath that's about 10kw a day on best days where it only takes about 6kw a day that's 2 or 3 showers.

 

So my options are 

 

Install a new all in 1 hybrid Air source water heater

 

Install a new thermodynamic water heating system 

 

I did toy with a back boiler to our stove but that means I would need to run my wood burner in the summer months to get hot water not ideal

 

Would anyone have advice

 

 

 

Insulate the F out of the tank.

 

If you do this you will probably require a digital thermostat to control the heating element and ducting to protect the element electric cable.

 

I used a digital thermometer to switch a 16amp relay.

 

I'm sure others will clarify.

 

I've done the above and the utility room with the tank in is no longer like an oven.

Edited by Marvin
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I have fitted a 200Lt tank in my house but will not be moving in for a month but it is up and running and keeps a tank of hot water and only kicks in to top up from heat loss when the tank goes below 50 degrees from 55. I think once a day. When running it uses the same as a fridge.

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On 21/06/2022 at 07:49, JohnMo said:

You don't really want to sucking all the heat out of the living space.  You need to do from wet rooms, this will also assist moving some air through the house

Pulling cold in from outside via draughts / trickle vents in winter = bad idea.

Edited by Nickfromwales
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23 hours ago, keith65 said:

I have fitted a 200Lt tank in my house but will not be moving in for a month but it is up and running and keeps a tank of hot water and only kicks in to top up from heat loss when the tank goes below 50 degrees from 55. I think once a day. When running it uses the same as a fridge.

Which one did you install?

 

Most have energy usage monitoring built in do you know any figures yet?.

 

Did you plumb the air vent internal or externally?.

 

 

Edited by Calw
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I have installed the SAHP 200,

I have not looked at energy figures as of yet will look at it more when I have moved in.

There is no air vent as it has an external panel with 2 10mm copper pipes attached where the refrigerant is pumped by the compressor these can be sealed with airtight grommets and tape as they pass through  wall. SAHP | Award-Winning Solar Assisted Heat Pumps

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