Replacement oil CH boiler

[PeterK]

The need to replace my oil boiler also allows (forces?) me to look at converting from a gravity HW pumped CH system. to a "sealed" system and unvented HW tank. Comments on the following please derived from plumbers merchants, manufacturers' sites and of course the newsgroup archives:

Non condensing boiler - the efficiency of conventional oil boilers such that the payback on going "condensing" is years? System boiler or add expansion vessel etc.outside the boiler ? - space not an issue , boiler either external or large utility room Convert to S Plan ? - May go for zoning if extant pipe runs suit. HW cylinder go for stainless or copper , expansion vessel or "bubble in tank", "ready plumbed" or add external components, makes to go for /avoid.

This is the planning stage so building regs and pressurised HW is not an issue at this stage - unless thermal stores are raised - I was going to ask but I think its a bit of a no go area for this newsgroup:-)

I thought about making this one or several posts but I went for one since I need a CH system. Apologies if I'm wrong.

Peter K

[Grunff]

I would recommend a thermal store (or heat bank if you want) with an oild boiler. We first tried our boiler (Grant Euroflame) with a conventional pupmed/vented setup, but found the boiler short-cycling quite a bit. We then switched to a heat bank, and found that this is much better suited to oil (you get nice, long burn times).

[Doctor Drivel]

That was the case, but the condensing prices have dropped a lot, so maybe worth going condensing.

Have the vesel external as makers own brands are expensive to replace. If external then a syetem boiler.

No go? It is a go. Take no notice of the amateurs. Go for a thermal store/heat bank as un unvented cylinder cannot be DIYed, and also they require an annual service charge. So you pay £60 to 80 a year just have a cylinder of water. They are a con so plumbing companies can get the population by the balls once a year. A nice little earner here and there for doing sweet FA. To test properly they would need to charge £150, as they would have to simulate failed controls, and none ever do that.

Thermal stores require no servicing, and can be DIYed. Also you can buy a fully packaged "integrated" thermal store that does the CH and DHW with all the pumps and controls. You just run the wire for the room stat and one to the bioler and connect to the mains. Then run the flow and return to the boiler and the flow and return to the rads.

Simple.

[Grunff]

And this is one of those rare times when Drivel makes perfect sense.

[Doctor Drivel]

..Grunff, Grunff, Grunff, Grunff ..a noise that's made by swine ..Grunff, Grunff, Grunff, Grunff ..he views the dirty bastards fine ..Grunff, Grunff, Grunff, Grunff ..a noise, a shieking grunt and shrill ..Grunff, Grunff, Grunff, Grunff ..the greedy bastards scoff the swill

..so when you see that name upon your monitor ..a pig so filthy is behind the moniker

[PeterK]

Gentlemen Congratulations on getting me to think again. I've looked at DPS

.From your description are you recommending a "Pandora" heat bank - large store of water heated by an indirect coil that heats the hot water using a heat exchanger ?

Any other suppliers known?.

Peter K

[Grunff]

Ours came from Range. The water is heated directly, by being pumped from the tank to the boiler and back. The same water is also circulated around the radiators. Hot water for the taps is heated either in a coil (thermal store) or heat exchanger (heat bank).

[Grunff]

That's just mean! Serves me right for trying to be nice to you.

[Doctor Drivel]

No, the CX. The Pandora is a DHW only heat bank. The CX is an integrated "direct" heat bank that will cut out inefficient boiler cycling and run the CH off the store too. Have a Grundfos Alpha pump on the CH circuit and then TRVs on all rads and no wall stat. Also have a Magnaclean filter on the CH return to the store. This will pick up all the maganite, and other solids, from the rads and prevent it accumulating in the store.

[Doctor Drivel]

But true.

[Roger Mills (aka Set Square)]

Who'd like to nominate Drivel as the next Poet Laureate? Maybe Andrew Motion should watch his back.

Or perhaps not!

[Roger Mills (aka Set Square)]

If you've got room, an external pressure vessel is better. the ones in system boilers seems to be proprietary - and more difficult and more expensive to replace.

I'd certainly go for an S-Plan system. It provides the greatest flexibility for having more than one heating zone. The alternative Y-Plan only provides one heating (plus one HW) zone - and the mid-position valve it employs is a frequent source of system failure. Whichever way you go you will, of course, have to do a certain amount of re-plumbing to bring everything into a single pumped boiler feed and return, prior to splitting into zones.

The perceived wisdom in this NG seems to favour thermal stores rather than mains unvented cylinders because you can DIY them and they present less safety hazzards. You don't *have* to have hot water at mains pressure, of course. Just because the primary circuit will be unvented, the main HW system doesn't have to be. Provided you've got a really good mains cold supply and a high capacity heat exchanger in your thermal store, mains has the advantage of not needing a booster pump for a shower. But if the mains isn't up to it, you would be better off with a conventional quick recovery indirect hot cylinder and header tank.

[Steve S]

"Roger Mills (aka Set Square)" wrote

Perchance a job swap? Maybe Andrew Motion knows how to make a clean cut in plastic pipe?

Steve S

[<me9]

I'm thinking of re-vamping my heating, and going for a thermal store. Are there any on-line suppliers. All I can find are the manufacturer's sites (albion mainsflow, and pandora), but no prices.

[Doctor Drivel]

And they don't cost £60-80 a year for an annual service, Unvented cylinders are a con, as better alternatives are around. Vented thermal stores "cannot" explode.

A quick Google brings up some.

at the makers. Ring them. Some sell direct, others will give a list of suppliers. Do Googles for on-line suppliers: