Thermal Store vs 'Traditional' Vented DHW/heating system

[mike.peppert]

We're about to have an extension built, which will necessitate the installation of a new boiler, (and cylinder). I am considering installing Solar DHW as well, (or at least installing a dual coil cylinder to enable that upgrade in the future.). A couple of quiet nightshifts and an awful lot of googling of this group suggests that I don't want a combi, (please no discussion of this; I see that it's been done to death one hundred times before!), so thought that I need a traditional vented DHW and cylinder system. However, the overwhelming opinion in this group seems to be that that is soooooo yesterday, and what I really need is a heatbank or thermal store.

(amongst other sites recommended here), provided useful information, and I have come to the conclusion, (again amassing evidence from this group) - that if I go down this line then I want a vented thermal store rather than a pressurised system. [again I see that this debate has been done to death!]

What I don't understand though is why I need a thermal store in the first place rather than just a 'traditional' vented system. My understanding of the advantages are; mains pressure hot water and.........

Is that all I get for the extra expense of a thermal store?

Of course I know I get the advantage of being 'hip and with it' and not using yesterdays technology, but when the system goes wrong and I need to find a plumber on a bank holiday weekend, (sacralidge to say of course this being a diy group!), is it such a bad thing being a dinosaur?

Hellllllllp

Mike

[Brian Sharrock]

wrote in message news: [e-mail]...

I almost did what you did, googled, researched and eventually went the heat web vented system - one year (Easter) ago.

You most definitely get the advantage of mains pressure (and potable - they tell me) hot water - which is not to be dismissed lightly. However the other advantage is that the thermal store acts as a huge buffer/accumulator for the boiler. I am still utilsing the Potterton Netaheat 10-16 installed in 1975 - changing that for a condensing model is a 'getting a roundit' exercise. The bolier cycles less frequently and my gas bill (calculated) has been reduced over this last year. With exactly the same bolier and "traditional vented system" it used to be a one bath plus wait a bit for the seconf bath water to re-heat exercise - frequently the 'second' bath could only be 3/4 full before the tank ran cold-ish. Since the introduction of the thermal store we can run two baths simultaneously and any subsequent bath doesn't run out of hot water. I've also never had an occurence of 'Oh! The hot tap is running cold - better switch the bolier ON' . One other advantages is that the heat store's water (I prefer to call it the 'working fluid' is distibuted through the CH system too - so at switch-on of the CH, that heat is availabe (almost )instantaneously and the radiator beome 'hot' quickly. [Obviously - there's owt for nowt - the heat has to coe from your boiler but it's been buffered] The effect is vaguely similiar to any accumulator system; air-compressor tank; hatch-back rear door dampers, etc. etc. in the case Heat is stored in the thermal stores 'working fluid' and can be surrendered into your DHW and/or radiators as required - the bolier circuitry will produce 'heat' and pop it back into the 'Store as and when require.

Effectively; whets to go wrong? OK, the elecktrickery might've gone off - which is a 'single point of failure' thing. Without electrickery to pump the water through the boiler and back into the Thermal store; you've no 'thermals' to 'store'. But gravity fed systems are like the Dodo and I believe all modern 'hip' systems rely on elecktrickery too. All the external components are bog-standard (off-the-shelf) items such as connectors and pumps and mixing valves ... and shouldn't faze any 'plumber' that you're likely to call out on a bank holiday weekend. If he's competent he should have a stack of pumps (Grundfos ) on his van' The only other components I can observe is the two Reliance wax-cylinder actuated mixing valves {One controls the boiler-store-working fluid temperature and the other the Working fluid-potable DHW temperature. The concept seems frightening - but the componentry utilised by 'heatweb.com' is all very reassuringly familiar - and available. :(

It's time to make the declaration - I have no connection with 'heatweb.com' ; other than as a very satisfied customer. They were very helpful - produced what I needed - having guided me- and assisted me to load the bubble-wrap swathed cylinder into my mondeo.

HTH

[The Natural Philosopher]

No, you need a mains pressure hot water tank.

No, you want a pressurised water system

Pressure.

nothingh. Just skads of hot water for showers that don;t either run cold (commbi) or dribble (vented)or need and electric pump.

Nothing TO go wrong.

Just stick a water softener to avoid scale in as well, and it will last forevere.

[meow2222]

couple that explain it very well here

one on solar thermal

Because the thermal store water is hotter than dhw, the tank stores more heat.

NT