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