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Hot water via a "Thermal Heat Store"... ?

Jim Audiomisc

Jim Audiomisc

pfm Member
I'm wanting to see if I can get and have installed an optimum way to have hot water just for hot tapwater that uses *electric* power,

. i.e. no central/house heating involved.. Nor gas heated. But supplies all the hot taps in the house.

IIUC the "Quooker" types of electrified tap can only cope with one tap, each, and are simply 'instant'. So can't take advantage of a cheaper off peak electric tariff.

I've found this page:

https://www.heatelectric.uk/sunamp/

Talking about "Water heater with Thermal Heat Stores". But longer on claims than tech info.

Anyone had these installed or know more about them? I'm wondering how much 'better' they might be than ye olde hot water tank plus a night-tarriff timered immersion. ..or if they have snags or fail after a time, etc?...
 
We have had one for a few years and it works perfectly well. We either top it up overnight on our cheap EV tariff using a myenergi Zappi controller or divert excess solar into it.
 
If anyone opts to have a split tarriff for electricity, the daytime rate soars and unless you use the very great bulk of all your electricity on the off-peak tarriff, you never make money. Been there, tried it, everything that uses any leccy that could be, on a timer - I have long been back on a single tarriff.

What you are talking about is a hot water cylinder with an immersion heater operating on off-peak. How does changing details and the name make it any different? At least with a hot water cylinder it is 100% efficient and only becomes less when you lose heat from the water.
 
One of my neighbours is in the process of installing one and for them it looks like it should work well as they're putting in a system that'll have various options (wood pellets or solar mainly) to provide energy. Another neighbour has one in a house he's recently bought and it doesn't work well at all, with the issue being pointed at the the heat store being too small for their house. They're likely to rip it out and install an oil fired combi instead.
 
We put in a thermal store in the old house 15 years ago. Tapped in solar thermal, a solid fuel Rayburn and a wood burner with back boiler. Had 12kw immersions as back up (never used them). It’s effectively a hot water battery which can be charged via multiple sources. Could have tapped in a ground source heat pump, oil boiler, whatever. A very flexible system which worked well in that environment (with own wood source). Although my current gas combi is far less hassle and still cheaper to run…
 
gingermrkettle said:
Which with solar and storage or if you have an electrical car, you do.
Click to expand...

Agreed, but heating a hot water cylinder on E7 is no different. Why complicate things?
Unless you do have storage from solar and/or an electric car, you will not save money anyway.
 
Jim Audiomisc said:
I'm wanting to see if I can get and have installed an optimum way to have hot water just for hot tapwater that uses *electric* power,

. i.e. no central/house heating involved.. Nor gas heated. But supplies all the hot taps in the house.

IIUC the "Quooker" types of electrified tap can only cope with one tap, each, and are simply 'instant'. So can't take advantage of a cheaper off peak electric tariff.

I've found this page:

https://www.heatelectric.uk/sunamp/

Talking about "Water heater with Thermal Heat Stores". But longer on claims than tech info.

Anyone had these installed or know more about them? I'm wondering how much 'better' they might be than ye olde hot water tank plus a night-tarriff timered immersion. ..or if they have snags or fail after a time, etc?...
Click to expand...

Think about your pipe runs too, for one sink i use an undercounter 15 litre tank. I get hot water after running the tap for a second and set it to a comfortable hand washing temperature, no waste.

Not adequate for a bath tap obvs!
 
Thermal stores are very good. Gledhill is the manufacturer who springs to mind. Gives you mains pressure on your hot water.
 
Just planning someones flat , it has a massive heater i think gledhill , and a very old boiler that heats separate rads .at the moment we are thinking its not very economic to heat all that hot water tank when a combi boiler just heats water on demand

But maybe the ops system is only electric so combi not an option ?
 
Our house had a "thermal heat store" but with a regular gas boiler. After ~15 years we changed to a combi which we prefer. The main problem was the store did shed heat albeit slower than a normal tank. It was underneath our master bedroom so in the summer, it wasn't ideal. Also failures of the store or related pipes could cause a more sudden big problem than with a combi.
 
Vinny said:
If anyone opts to have a split tarriff for electricity, the daytime rate soars and unless you use the very great bulk of all your electricity on the off-peak tarriff, you never make money. Been there, tried it, everything that uses any leccy that could be, on a timer - I have long been back on a single tarriff.

What you are talking about is a hot water cylinder with an immersion heater operating on off-peak. How does changing details and the name make it any different? At least with a hot water cylinder it is 100% efficient and only becomes less when you lose heat from the water.
Click to expand...

For us choice of tariff is a seperate issue. May well go on using the standard tariff. AIUI the 'heat stores' use a phase-change material to store/release heat with the water as the transfer medium. This means they should behave differently to a conventional hot water tank. e.g. you can add or remove heat without a large temperature change in what is 'in the store'. That may also mean lower rate of loss of stored head via conduction to outside the container. Hence could be more efficient in terms of avoiding unwanted loss.

Devil would be in details I don't yet know.

Also, for us this is simply for 'hot taps' water. NOT for 'central heating of the house'. That we already do by other means that suit us.
 
gingermrkettle said:
Our experiences are that the heat losses from a Sunamp are less than that of a hot water cylinder.
Click to expand...

That's what I'd have expected / hoped for in principle given how they seem to work. Thus for a 'hot water reservoir' the heat store may be more efficient than a conventional hot water tank + immersion. Question of how well designed and made they are.
 
dweezil said:
Think about your pipe runs too, for one sink i use an undercounter 15 litre tank. I get hot water after running the tap for a second and set it to a comfortable hand washing temperature, no waste.

Not adequate for a bath tap obvs!
Click to expand...

Bath and a tiny upstairs loo with limited access for elecric is one aspect of this for us. And by square/cube rules one bigger store should be more efficient than two or three smaller ones of the same total capacity. Also simpler to install. FWIW we have a place in the kitchen where our failed old boiler still lurks. I'm hoping the new device will go there and the boiler will be junked. (Thus a side-issue is filling in the hole of the redundant flue.)
 
hifinutt said:
Just planning someones flat , it has a massive heater i think gledhill , and a very old boiler that heats separate rads .at the moment we are thinking its not very economic to heat all that hot water tank when a combi boiler just heats water on demand

But maybe the ops system is only electric so combi not an option ?
Click to expand...

We've given up on conventional 'water-circuit' radiators. PITA. Use other means (mix of gas fire and electric). The aim now is just for having an updated hot water system for the hot water taps. In effect we are grading out relying on gas as we approach the time when things will be all electric inc solar PV not water-piped.

FWIW If you read things like IEEE 'Spectrum' you can see that solar PV, wind, etc, are rapidly getting better. Main issues we can foresee are 'political' in that area not engineering per se.

Similarly, my main concern with the thermal heat store idea is to find a *reliable* seller/installer who will do a decent job promptly and not leave any new 'issues' - damage, flaws, etc. Our general experience in recent years of plumbers, etc, is shoddy work that can break more than it mends seems the norm! :-<
 
darrenyeats said:
Our house had a "thermal heat store" but with a regular gas boiler. After ~15 years we changed to a combi which we prefer. The main problem was the store did shed heat albeit slower than a normal tank. It was underneath our master bedroom so in the summer, it wasn't ideal. Also failures of the store or related pipes could cause a more sudden big problem than with a combi.
Click to expand...

Ours would ideally be under the kitchen worksurface. What failures did you get? Who made/installed it?
 
Jim Audiomisc said:
We've given up on conventional 'water-circuit' radiators. PITA. Use other means (mix of gas fire and electric). The aim now is just for having an updated hot water system for the hot water taps. In effect we are grading out relying on gas as we approach the time when things will be all electric inc solar PV not water-piped.

FWIW If you read things like IEEE 'Spectrum' you can see that solar PV, wind, etc, are rapidly getting better. Main issues we can foresee are 'political' in that area not engineering per se.

Similarly, my main concern with the thermal heat store idea is to find a *reliable* seller/installer who will do a decent job promptly and not leave any new 'issues' - damage, flaws, etc. Our general experience in recent years of plumbers, etc, is shoddy work that can break more than it mends seems the norm! :-<
Click to expand...

We use an Immersun to divert xs electricity to a 300 litre hot water tank which works well in the summer.

It's not particularly sophisticated (unlike the Sunamp?) but with a 4kW set of panels we could heat enough water for two showers eight months of the year, in summer just about a big bath on a sunny day.

The Gledhill tank is well insulated and it's got a coil for oil backup if there isn't enough hot water by 17-00.
 
Vinny said:
If anyone opts to have a split tarriff for electricity, the daytime rate soars and unless you use the very great bulk of all your electricity on the off-peak tarriff, you never make money. Been there, tried it, everything that uses any leccy that could be, on a timer - I have long been back on a single tarriff.
Click to expand...
I take it factual accuracy isn't a pre-requisite on the forum?

Just taken this off the Octopus Watch app on my phone:-

GzXijt8.jpg


OK so I'm using batteries and they had to be bought, yes they'll deteriorate and yes they'll need replacing in due course.

I get a little fed up with naysayers who are either poorly informed or continue to perpetuate things they read else where on the inter web or didn't do their homework in the first place.

The Sunamp would seem to be an efficient system but yes you'll need a smart meter and to be on a suitable tariff to 'make it work'. It would be more effective still against a background of having an EV, a Solar PV system and also storage batteries. I'm not sure how well it would stack up if you already had or were thinking of getting a heat pump installed though as I have no direct experience.

Regards

Richard
 
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