Heat Banks and Thermal Stores

[HarryM]

I inadvertently raised this question in the Electrics UK forum, so am posting it again here.

I am considering installing a thermal store hot water cylinder which will be powered by an on-peak immersion heater only. It's for hot water only and there is no central heating. It needs to supply a bathroom basin. a kitchen sink, and occasionally a bath (I normally use an electric shower.)

The apparent advantages include being able to site it downstairs with no need for an overflow pipe or cold water tank, easier installation, and no annual maintenance.

But I don't know anything about them apart from what I have read on the internet. Are there any pros and cons? How do they compare with an unvented cylinder for example?

 

[Moss5]

This link from another forum: -
http://www.screwfix.com/talk/thread.jspa?threadID=32064&tstart=120

Thermal Store
This is simple and has a large Dhw immersed coil for DHWE take off. The flows are generally not as good as an unvenetd cylinder or heat bank.

Heat bank:

The same as a thermal store, except it uses a standard CH pump and a high efficiency plate heat exchanger. The flows can be higher than an unvented cylinder.

Look at http://www.heatweb.com for an explanation and comparison.

Some of the makers - there are more. Ring them. Some sell direct, others will give a list of suppliers. Do a Google for on-line suppliers. Many will make to order.

http://www.newarkcyl.freeserve.co.uk
http://www.mcdonald-engineers.com
http://www.rcmgroup.co.uk/
http://www.telford-group.com
http://www.elsonhotwater.co.uk/
http://www.heatweb.com
http://www.albion-online.co.uk
http://www.range-cylinders.co.uk
http://www.gledhill.net (an extensive range)
http://www.chelmerheating.co.uk

 

[HarryM]

Moss5, thanks for the info. I suspect a Thermal Store would suit my needs, providing the price is right!

Any recommendations on manufacturers, or those to avoid?

 

[Moss5]

Sorry, I have no personal experience of these. I've just been reading the arguments with interest.

 

[kevplumb]

read some of doitall's then

 

[HarryM]

Kev,

Doitall has made about 1500 posts. Which ones did you have in mind?

 

[croydoncorgi]

I am considering installing a thermal store hot water cylinder which will be powered by an on-peak immersion heater only

If you're planning to use on-peak electricity, why go to the extra expense of a thermal store? You'll gain nothing over a well-insulated direct-heated hot water cylinder.

Also, if you're in a hard-water area, watch out! The heatstore will normally operate at 80+ degrees. this is fine for the water that just sits in the cylinger and stores the heat. The problem is the mains water sitting in the hot water coil while all the taps are off. After a short time, this will be at the same temperature as the 'store and probably above the 'critical temperature' when 'temporary hardness' cooks out of the water. Result: limescale inside the coil and frequent descaling unless you take precautions. Better makes of heatstore have a 'siliphos' gadget on the cold supply, to prevent limescale problems.

 

[kevplumb]

Kev,

Doitall has made about 1500 posts. Which ones did you have in mind?

try gledhill sludge bucket's

J D loves em

 

[HarryM]

Croydon,

I agree. My problem is I had an old hotwater cylinder situated in the dining room which was originally heated by an Aga. The Aga had disappeared before I bought the house and the cylinder ran from an immersion heater. I removed it when renovating the dining room as it took up an enormous amount of room with a cupboard at an angle across one corner. For the last few months I have been living with an electric shower which fortunately had a shower head which could reach the bathroom basin, and only cold water downstairs. This should have been sorted weeks ago, but problems and delays with builders...

The cheapest solution is another cylinder upstairs, but the floor loading is a problem. It's an old house and the beams weren't really meant for that sort of weight. They have also been perforated in places where cables have been laid, and the same beams also carry the weight of the bath.

I have lots of room downstairs in an outbuilding adjacent to the kitchen, which seems the ideal location. It's even got a concrete plinth where a washing machine used to stand. But it's not suitablel for a normal direct cylinder as it would be difficult to provide an overflow back to the loft tank. (Unless I ran it up the disused kitchen chimney and broke out into the loft. )

So I have been looking at LPG water heaters and unvented cylinders, until I recently came across heat stores which looked a better prospect. It's a very soft water area, so scaling is not a problem.

Unfortunately all the ones I have been able to find prices for seem very expensive for such a simple product! If I could get one for £350 or so, that would probably be as cheap as a normal cylinder when the installation costs are taken into account.

Kev,

I have seen the Glenhill Torrent, but the internet price for a 160L is £595. Yikes!

 

[kipperman]

just my pennyworth- have just completed DIY install of new CH and water supply in major extension. Fitted a 250L heat bank from DPS ( heatweb.com). We are (I believe) lucky in having about 4 bar water pressure- but extremely pleased with set up, with very good flow rate through showers- so much so that only need to open valve by a quarter. Not a pressure vessel, so DIY install fine. Despite two showers and a bath, haven't actually managed to get any drop in supplied temperature.

 

[chrishutt]

I am considering installing a thermal store hot water cylinder which will be powered by an on-peak immersion heater only

Why on earth don't you use Economy 7 or 10? Then a thermal store would make more sense.

 

[croydoncorgi]

have just completed DIY install of new CH and water supply in major extension. Fitted a 250L heat bank from DPS ( heatweb.com).

What boiler is on it and what temperature is the store operating at?

I can't understand at all how a 'high efficiency' boiler can be expected to operate efficiently when connected to a tankful of water already at 75+ degrees!

 

[kevplumb]

it can't
you will never get the temp diff

 

[HarryM]

I am considering installing a thermal store hot water cylinder which will be powered by an on-peak immersion heater only

Why on earth don't you use Economy 7 or 10? Then a thermal store would make more sense.

I don't currently have Economy 7. To switch to it for just an immersion heater would raise my costs for normal daytime usage.

I estimate my old vented tank with immersion heater cost about £18/quarter to run as it was on for only 45 mins each night. (Except for a few weeks per year when I had visitors.)

I am assuming a thermal store will cost the same or even less. The temperature of the stored water will be higher, and therefore the potential rate of heat loss will be higher due to the greater internal/external temperature difference, but this should be offset by the better insulation compared to my old cylinder.

 

[Nige F]

I have lots of room downstairs in an outbuilding adjacent to the kitchen, which seems the ideal location. It's even got a concrete plinth where a washing machine used to stand. But it's not suitablel for a normal direct cylinder as it would be difficult to provide an overflow back to the loft tank. (Unless I ran it up the disused kitchen chimney and broke out into the loft. )

. Yikes!

plastic pipe..up yer flue(ohMatron)with lagging .easy as sweeping the flue.apart from knocking the hole...Cheapest option Life is complex enough without themal stores