Cylinder for DIY thermal store

[siricosm]

I am looking to install a thermal store to replace my current vented cylinder. I plan to use an external plate exchanger for DHW and heat the store directly from my existing vented boiler. So what I am looking for is a plain stainless steel tank (no internal coils) with a variety of connections. It would need to have at least 2x22mm (or bigger) towards the top, at least 2x22mm at the bottom, a place for a cylinder stat, and a connection for a backup immersion heater.

So far I have found the Gledhill Flexible Buffer store (PLU300MB) that looks like could work, although it would be nice if it had 2 stat pockets and the upper connections were spread out (vertically) a bit, like in their regular buffer store PLUDR300B. Unfortunately the PLUDR300B does not have a spot for an immersion heater.

Any one know of anything similar from other manufacturers?

 

[EvilDrPorkChop]

I am looking to install a thermal store to replace my current vented cylinder. I plan to use an external plate exchanger for DHW and heat the store directly from my existing vented boiler. So what I am looking for is a plain stainless steel tank (no internal coils) with a variety of connections. It would need to have at least 2x22mm (or bigger) towards the top, at least 2x22mm at the bottom, a place for a cylinder stat, and a connection for a backup immersion heater.

So far I have found the Gledhill Flexible Buffer store (PLU300MB) that looks like could work, although it would be nice if it had 2 stat pockets and the upper connections were spread out (vertically) a bit, like in their regular buffer store PLUDR300B. Unfortunately the PLUDR300B does not have a spot for an immersion heater.

Any one know of anything similar from other manufacturers?

Why the thermal store and not an Unvented cylinder? Have you got external heat sources like Wood burners etc.

 

[siricosm]

Why the thermal store and not an Unvented cylinder? Have you got external heat sources like Wood burners etc.

In addition to mains pressure hot water, I would like to have heat flowing to the radiators whether the boiler is running or not. My heating loop will use a modulating pump (Grunfos alpha 2) and TRVs all round.

 

[centralheatking]

I am looking to install a thermal store to replace my current vented cylinder. I plan to use an external plate exchanger for DHW and heat the store directly from my existing vented boiler. So what I am looking for is a plain stainless steel tank (no internal coils) with a variety of connections. It would need to have at least 2x22mm (or bigger) towards the top, at least 2x22mm at the bottom, a place for a cylinder stat, and a connection for a backup immersion heater.

So far I have found the Gledhill Flexible Buffer store (PLU300MB) that looks like could work, although it would be nice if it had 2 stat pockets and the upper connections were spread out (vertically) a bit, like in their regular buffer store PLUDR300B. Unfortunately the PLUDR300B does not have a spot for an immersion heater.

Any one know of anything similar from other manufacturers?

Gledhill ...Uck there has never been anything decent come out of that Blackpool outfit
centralheatking

 

[siricosm]

Gledhill ...Uck there has never been anything decent come out of that Blackpool outfit
centralheatking

Yes, I have read a lot of complaints about them, which is why I am looking for other makes.

 

[ShaunCorbs]

Why not use a twin coil unvented in reverse

eg gledhill 400l sol

use the twin coils for hot water etc?

 

[siricosm]

Why not use a twin coil unvented in reverse

eg gledhill 400l sol

use the twin coils for hot water etc?

Typically the coils are too small (1-2 m^2 surface area), even in most commercial thermal stores, which is why people think stores need to run at 80C to work. I plan on running mine at 60C. I also live in Norwich, which has very hard water and I am worried a bit about internal coils scaling as well.

Something like this would work, the 300l version has a 4.1^2 area coil:
Hygienic Buffer Storage Tank Vertical - http://plumbingsupplies24.co.uk/hygienic-buffer-storage-tank-vertical/

But it is a mild steel tank, so it would need to be a sealed system. In the UK people are a bit fearful of sealed hot water systems, so there are a lot of hoops to jump through for a DIY install.

 

[ShaunCorbs]

Typically the coils are too small (1-2 m^2 surface area), even in most commercial thermal stores, which is why people think stores need to run at 80C to work. I plan on running mine at 60C. I also live in Norwich, which has very hard water and I am worried a bit about internal coils scaling as well.

Something like this would work, the 300l version has a 4.1^2 area coil:
Hygienic Buffer Storage Tank Vertical - http://plumbingsupplies24.co.uk/hygienic-buffer-storage-tank-vertical/

But it is a mild steel tank, so it would need to be a sealed system. In the UK people are a bit fearful of sealed hot water systems, so there are a lot of hoops to jump through for a DIY install.

each coil is 20 kw so if you combine them that should give you a hot water of around 20kw (to be safe)

why not just buy a thermal store? as there designed for what your planning?

 

[siricosm]

each coil is 20 kw so if you combine them that should give you a hot water of around 20kw (to be safe)

why not just buy a thermal store? as there designed for what your planning?

Aside from being overpriced, most commercial thermal stores are not designed to deliver 12lpm of hot water while running at 60C. The DHW coils are too small. There are a few exception like the steel OEG store I linked above, I lived with that one for a few years in my previous house and it worked great. It has a 4.1sq.m corrugated stainless coil, so I that would be around 150kW given an average differential of 30C and an estimate of 1.2 kW/m2/k for the coil. To get 12lpm of hot water from 5C to 40C you need 30kW. The problem is that exchangers are typically rated for a 40C differential, which is not realistic for a 60C tank. Drop that to around 12C differential and you need 100kw. A 100kW plate exchanger is pretty cheap, and serviceable.

 

[ShaunCorbs]

if you suffer from hard water plate hex is out of the question as it will get blocked very easily and once it blocked you will need to replace it

have a word with these people

Vented Hot Water Cylinders | Vented Hot Water Cylinders | Bespoke

McDonald Water Storage have been providing vented and unvented hot water cylinder solutions for over 75 years. Our expert team of engineers are able to

www.mcdonaldwaterstorage.com

gledhill make a 3.7m2 coil on there thermal stores also they do one with an external plate

 

[siricosm]

if you suffer from hard water plate hex is out of the question as it will get blocked very easily and once it blocked you will need to replace it

have a word with these people

Vented Hot Water Cylinders | Vented Hot Water Cylinders | Bespoke

McDonald Water Storage have been providing vented and unvented hot water cylinder solutions for over 75 years. Our expert team of engineers are able to

www.mcdonaldwaterstorage.com

Does that mean you can't use a combi in Norwich?

 

[ShaunCorbs]

Does that mean you can't use a combi in Norwich?

you can but you replace a fair few plates or set up a softener (which i bet most people do

 

[siricosm]

have a word with these people

Vented Hot Water Cylinders | Vented Hot Water Cylinders | Bespoke

McDonald Water Storage have been providing vented and unvented hot water cylinder solutions for over 75 years. Our expert team of engineers are able to

www.mcdonaldwaterstorage.com

gledhill make a 3.7m2 coil on there thermal stores also they do one with an external plate

Thanks, I will try to get a quote from McDonald.

How did you find out how big the DHW coil was in the Gledhill? and which model has the 3.7 sq. m. coil? Most of the manufacturers don't seem to list the coil sizes or even the ratings.

 

[ShaunCorbs]

Thanks, I will try to get a quote from McDonald.

How did you find out how big the DHW coil was in the Gledhill? and which model has the 3.7 sq. m. coil? Most of the manufacturers don't seem to list the coil sizes or even the ratings.

in there instructions lists the coil values in there

https://www.gledhill.net/uploads/Torrent-Stainless-Iss-4.1-1.pdf

 

[Chuck]

But it is a mild steel tank, so it would need to be a sealed system. In the UK people are a bit fearful of sealed hot water systems, so there are a lot of hoops to jump through for a DIY install.

These days, vented hot water installations are subject to LABC notification requirements too. If you’re not a member of a CPS, you need to notify your LABC before and after installation. They'll want to check that you are competent and probably visit while the work is being undertaken.

 

[siricosm]

These days, vented hot water installations are subject to LABC notification requirements too. If you’re not a member of a CPS, you need to notify your LABC before and after installation. They'll want to check that you are competent and probably visit while the work is being undertaken.

I will definitely be in touch with building control. I have always had good experiences in the past, and I have found that if your work is neat and correctly done, they are usually very agreeable. I am still unsure if a sealed low pressure (2 bar) store with an external plate exchanger requires G3. I have read that it is a grey area, so I am going to ask them directly, and if I am allowed I will seal it. If not I will go with the F&E for the primary water (does any country other than the UK still use F&E tanks?). We are also planning to build an addition in a couple years time. Then we will likely have to replace our Ideal FF360 that came with the house, as it will need to be moved. At this point the guy/gal selling me the boiler might be able to seal it all up as well.

So I am looking for a plain (no coils) 300l tank with fittings described above that could be used in a vented or low pressure (2 bar release) sealed setup.

I would also go for a mild steel tank with a large stainless coil for DHW (like the OEG I linked above) if I could find a G3 in Norwich to commission it for me.

 

[centralheatking]

I will definitely be in touch with building control. I have always had good experiences in the past, and I have found that if your work is neat and correctly done, they are usually very agreeable. I am still unsure if a sealed low pressure (2 bar) store with an external plate exchanger requires G3. I have read that it is a grey area, so I am going to ask them directly, and if I am allowed I will seal it. If not I will go with the F&E for the primary water (does any country other than the UK still use F&E tanks?). We are also planning to build an addition in a couple years time. Then we will likely have to replace our Ideal FF360 that came with the house, as it will need to be moved. At this point the guy/gal selling me the boiler might be able to seal it all up as well.

So I am looking for a plain (no coils) 300l tank with fittings described above that could be used in a vented or low pressure (2 bar release) sealed setup.

I would also go for a mild steel tank with a large stainless coil for DHW (like the OEG I linked above) if I could find a G3 in Norwich to commission it for me.

Let us all know how you get on in the New Year, in fact the next decade ...centralheatking

 

[siricosm]

So after looking around a while for a plain 300 liter stainless cylinder with enough connections I find:
1) Gledhill flexible buffer store
2) Telford standard buffer (1/2 price of the Gledhill, with 3K immersion, dual stat, and TPRV included)
3) Joule buffer (4x the Telford price at Plumbcity Norwich for the bare tank)
4) McDonald Stainless buffer (2x the Telford price, but sadly no immersion possible)

So it looks like the Telford wins, by a significant margin.

Are they any good? They appear to have a 10 year guarantee. Has anyone anything good/bad to say about them? Any other options?

 

[exedon2]

Try Newark cylinders have bought several special cylinders/ thermal stores from them
Delivery bit pricey I'm lucky to be near enough to collect

 

[siricosm]

Try Newark cylinders have bought several special cylinders/ thermal stores from them
Delivery bit pricey I'm lucky to be near enough to collect

I did look at this one:
2060x550 Stainless Steel Buffer Vessel (290 Litre) - https://shop.newarkcoppercylinder.co.uk/2060x550-stainless-steel-buffer-vessel

Again about twice the price of the Telford with no immersion boss.