Thermal stores - makes?

Hi all,

This has been done to death in the past... But I'm looking to see if there's any new developments I've missed.

I want a thermal store/heatbank, about 200-220 litres in capacity, for a fully open vented system, to buy next March.

So far:

DPS - about 1750 quid McDonald Thermflow - 890 Gledhill boilermate - 1300

(Prices inc VAT, not exactly comparable, eg McDonald would need some extra immersions, all except Gledhill need me to build relay control panel)

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DPS is nice and the company is easy to visit (Epsom) and I like being able to specify everything and the use of largely standard ancillary components (fixable easily, even if the company goes splat). But, well, it's rather expensive for a tank with 3 pumps, 3x3kW of immersions and a couple of mixers.

Gledhill is a nice appliance but full of specialist bits (cf DPS). I don't think this one uses a plate exchanger either for HW.

McDonald - harder to specify and they're in Scotland. But more the sort of money I'd expect to pay for a fancy tank.

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Any other suggestions?

What I'd really like to see is one that had variable speed pumps to regulate HW temperature and boiler return temp, rather than mixers. Would seem to be better at maintaining stratification. But I haven't found anyone who does this.

I'd also like a simple system, which is where DPS wins (and maybe McDonald):

1) One control loop and pump for boiler (direct heating to tank water mass is fine) - twin stats and a hysteresis loop would be good.

2) One control loop for HW

3) One control loop for heating (direct from tank water mass is fine).

4) Electric heating override.

5) Solar input coil for possible later use would be cool.

and none of them need to be electrically interconnected - use of computers is IMO unnecessary and one more thing to go wrong.

All ideas welcome.

Cheers

Tim

Reply to
Tim S
Loading thread data ...

Tim S coughed up some electrons that declared:

OK - I lied. Boilermate OV (open vented) (and it's solar option sister) do have a plate exchanger for HW.

And upon further reading, it uses a modulating pump for the HW (and for solar on the related model).

I must recheck that my quote was correct, for if it is, it looks a better system for 400 quid less than the DPS. OK, it has a fancy computer board which costs anywhere upto 200 quid to replace, but there's going to be compromises...

Spare parts seem readily available and, barring the control board, at reasonable prices.

Any other vendors worth looking at?

Cheers

Tim

Reply to
Tim S

I recently saw a 500 litre AKVA tank in operation and it certainly does the business. I think they sell a couple of versions. The one I saw had a full height coil for DHW and a lower solar coil. It also had numerous bosses and the chap told me they had helluva game getting suitably fitting blanks as nothing was supplied. So its a great piece of kit, but you will definitely have to do some legwork if you get one.

Dave

Reply to
Dave Starling

Dave Starling coughed up some electrons that declared:

Ah, one of these:

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notice they do a 300l which is more the size.

Could do with reading a manual on it.

Cheers

Tim

Reply to
Tim S

These make stainless stores and heat banks. They will make custom, to order - about 3 weeks delivery A heat bank, they will provide all the components and you assemble. They are in the Midlands. Good stuff.

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at:
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(make square storage vessels and thermal stores)
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(make heat banks and storage vessels to size)
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(make thermal stores and storage vessels)
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(make cylindrical heat banks and storage vessels)
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(make heat banks and storage vessels)
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(make cylindrical thermal stores and storage vessels. They are quite cheap)
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(make cylindrical thermal stores and storage vessels. Tristore)

Reply to
Doctor Drivel

They will also make a pressurised thermal store or heat bank. Then a system boiler can be fitted directly - without coils. Also the heating circuit too.

Copperform do a copper pressurised thermal store - internal coil.

Reply to
Doctor Drivel

Gledhill also do the torrent:

Reply to
Doctor Drivel

gledhill is also gone bust. KEep a way or loose yourmoney

Reply to
badbadwolf_uk

Gledhill has not gone bust. One division folded. They are trading as normal and not under administration.

Reply to
Doctor Drivel

Reply to
badbadwolf_uk

badbadwolf snipped-for-privacy@yahoo.co.uk coughed up some electrons that declared:

Well, to be exact, half has gone bust - specifically the half that did the interesting products from my POV.

Cheers

Tim

Reply to
Tim S

Doctor Drivel coughed up some electrons that declared:

I'd don't think the Torrent is suitable unfortunately - I'm looking for a system that will power the rads too (load smoothing on the boiler).

After having done a lot more reading, I've made two observations (which agree with the wiki entry on heatbanks):

1) Plate exchangers for HW probably produce greater power transfer = flow; But, with an uncontrolled pump, they are liable to wreck the stratification in the bank. Gledhill dealt with this by means of a temp sensors to modulating pump control loop. No-one else does this AFAICS. Even the pump (Grundfos UPR 15-50) is a bit of a weirdy - not even mentioned on Grundfos's website, but can be bought as a Gledhill spare part easily enough, meaning, that given time, I could adapt one onto a DPS bank and make my own controller (AVR cpu won't be difficult, simple closed loop control with a bit of damping should do it). 2) Internal coil exchangers for HW probably destroy the stratification less and need no pump and are inherently self balancing, and may be a good solution along as it can deliver the power transfer for a good HW flow rate.

I'm not sure why more manufacturers don't use modulating pumps.

Cheers

tim

Reply to
Tim S

Doctor Drivel coughed up some electrons that declared:

bubbles than worry about blowing things up. Irrational, perhaps, but I understand open vented systems and I like them.

Cheers

Tim

Reply to
Tim S

Doctor Drivel coughed up some electrons that declared:

Thanks for this :)

Quick reordering:

I've studied most of those guys - McDonald are cheap but DPS have more flexibility is my immediate conclusion.

Good stuff is dead :(

These all look fairly basic.

I think DPS is looking like the best bet. I could leave the way open to modify the system later - apart from the core tank all the bits are pretty standard.

There doesn't seem to be very much innovation in this field. Most of these guys are metal bashers and one that tried to innovate dropper dead.

Cheers

Tim

Reply to
Tim S

Now copperform.

They are in the Midlands. Good stuff.

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me what you want and I will narrow it down.

Reply to
Doctor Drivel

DPS use a Danfos RAKV valve to restrict the flow and maintain the DHW temperature.

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use a very large plate heat exchanger - 150 kW. These are very efficient and will work at a very low store temperature. This means if stratification is messed up somewhat or the temperature is just low they deliver the DHW.

Stratification is not messed up too much as the volume of water in the cylinder is quite large and the DHW pump pumps the right way. The boiler pump pumps the wrong way but very hot water is pumped into the top of the cylinder, so not a problem.

A spreader can be fitted on the DHW return. Drill out a compression fitting pipe stop and slide in the pipe. Have an internal pipe stop end. Drill holes in the pipe and have the holes face downwards. All pumps must pump away from the store.

The bottom of the cylinder can be very cool - 30C, while the top 75C. High condensing efficiency is guaranteed for most of the re-heat burn.

Have a Smart pump on the CH flow with a check valve after. Have a Magnaclean filter on the CH loop return - essential. With a Smart pump you can have TRVs all around.

Look at: AVANTA 18v System Only Option 6

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is a dual temperature boiler. The Broag 18V is open vented with an internal weather compensator. It is very well priced and a quality Dutch product. An external 3-way valve is energised by two anti-cycle stats on the upper part (DHW) of the store. All the boilers heat at full temp, goes to reheating the DHW. When satisfied the 3-way valve diveerts to heating only the bottom section to the dictates of the weather compensator.

The room stat is linked out and the 3-way valve is controlled by the boiler. The cyl stat is wired into the boiler. (the two stats using a relay). Just buy an outside weather temp sensor.

Then the rad water is at the right temperature and in a large volume in the store too preventing boiler cycling. No mixing valves are needed for CH as all is done by the boiler controls.

Advance Appliances will put the probes and tappings in the place you specify. They will provide the plate heat exchanger and most of the bits and you just connect up. They don't like to connect up electrical parts as they need to test have certificates etc.

Why when a Danfos valve can give the DHW temp and restrict pump flow?

Reply to
Doctor Drivel

Doctor Drivel coughed up some electrons that declared:

Cheers

Tim

Reply to
Tim S

That is a two-port valve. You can use a 3-port diverter body and have one port back to the store and the other back to the other side of the pump. Then the pump will never pump on nothing. If the hot port is closed it pumps back on itself. After the port back to the suction side of the pump fit an adjustable restrictor valve to balance up.

Reply to
Doctor Drivel

That is a RAVK.

Reply to
Doctor Drivel

Doctor Drivel coughed up some electrons that declared:

Brilliant, thanks.

I'm going to see DPS at their factory in the new year. Looking like I should use one of their standard GX heatbanks and stick a RAVK valve in appropriate places along with a self modulating Alpha pump (which are more common than the external control modulating).

Cheers

Tim

Reply to
Tim S

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