Standard or "Superduty" hot water cylinder?

I am on the point of deciding on a new hot water cylinder and I am now wondering about getting a "Superduty" cylinder - a cylinder with instead of a primary coil of one tube, a cylinder having a coil with four smaller tubes and hence greater surface area to transfer heat. Now the idea is to improve efficiency by reducing cycling and also reducing the temperature of the return flow and promote condensing.

" The installation of a Superduty will reduce boiler operating times and cycling periods resulting in savings of up to 40% compared with systems using conventional indirect cylinders."

40% is I am sure BS but is a decent efficiency saving likely?

And before anyone suggests it - no I f***ing well do not want a combi.

H
Reply to
HLAH
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40% is about right. Check if the figures were pre-Part L. If pre-Part L, then 40% is right. Then it will be about 33% compared to a Part L. You can also downsize the cylinder too.

You should consider a combi first. They make some fabulous models now.

Reply to
Doctor Drivel

Cheers for that it seems a worthwhile small extra investment then.

I'm sure there are but I still don't want one :-)

H
Reply to
HLAH

"HLAH" wrote .

Having paid particular attention to boiler posts over recent months, the problems encountered seem to relate to the complexity of control and electronics in the modern condensing units, rather than whether they include the hot water generating "combi" element.

Phil

Reply to
TheScullster

Depends also on what flow you want. It's easy to get high flow in the average house from a storage system to fill say a bath quickly - until of course that store runs out. But that's why storage cylinders are the size they are. And a fast recovery type will re-heat in the time it takes for a leisurely bath. No domestic combi will match this flow at the same temperature, and those which get closest ain't cheap. There's also the problem that in many parts of the country water pressure is low in an attempt to combat mains leaks. This can reduce the potential of any combi system even further. See the heating FAQ - it gives chapter and verse.

Reply to
Dave Plowman (News)

These are exactly the reasons why I don't want a combi. Everyone I know who has been sold one on the basis of the benefits has been dissapointed. Mainly because of dissapointing flow.

The mains pressure here is around 1 Bar and I suspect sometimes less when it's been dry for a while and everyone is watering their gardens. Not being able to have a power shower without difficulty is not acceptable as far as I am concerned.

Also I neglected to mention we are planning a solar installation so a big storage cylinder seems like a very good idea to improve the efficiency and reduce the payback time.

H
Reply to
HLAH

All in all, it should be well worth having the faster cylinder - especially if you have a condensing boiler to heat it. However be careful about what you expect to "save" here. It going to be mostly time rather than energy. A given mass of water will still take the same amount of energy to raise its temperature. Also a modern boiler will modulate to match the actual heat extraction rate of the coil in the cylinder - which will go a long way to reducing much cycling on even a relatively "slow" cylinder (reducing the cycling *does* reduce the fuel used a little).

Reply to
John Rumm

Sort of my thoughts. Unless you have an ancient system with a boiler than cycles continuously 40% saving is pie in the sky.

Reply to
Dave Plowman (News)

But that was tripe.

Then get a highflow combi. Do a search on this group for Alpha CD50 a few satisfied users. who will confirm the flowrates. They will a bath as fast as any storage system and no tanks or cylinders. Just because your mates have put in an inappropriate models does not mean they are all like that. Find out.

Is that 1 bar static pressure, with nothing flowing?

Ah he missed lots out. If you do have dire water mains pressure, this usually improves when a new 25mm plastic mains pipe is fitted, then fit a loft tank and heat bank. Heat banks are superb for mixing different heat sources and ideal for solar. Have a pump on the tank to heat bank line to give high pressure water at "all" taps. When the mains is updated in the road then you can strip out the tanks and pumps and go direct from the mains. Have an integrated heat bank running the CH from it. It is the best solution and gives great scope and flexibility for the future too.

Reply to
Doctor Drivel

Dribble reinventing the laws of physics again. And he claims to have a degree...

Reply to
Dave Plowman (News)

Can you run a power shower with that?

I suspect all rather more expensive than the £419 tank that I am going to have fitted.

H >
Reply to
HLAH

A good as your mains pressure can deliver.

With a solar coil as well? And an expensive shower pump too. Up the price a bit, a lot, it will all mount up. The heat bank is as I explained. It will do all together and be future proof.

Reply to
Doctor Drivel

Oh so crap for here then. No thanks I want a really good shower.

Yes

And an expensive shower pump too.

No not a very expensive pump.

Up the price a

H
Reply to
HLAH

Doesn't matter as you are going solar panels. Although a good mains pressure is highly desirable. What is it like after a new plastic pipe is run in? A few neighghbours must have had it done.

Cheap ones are not worth the hassle.

Very well worth considering.

Reply to
Doctor Drivel

A 40% saving in time to reheat could be feasable... (in fact a decent fast recovery cylinder should be able to swallow at least 20kW, some of the older standard ones may not be able to use more than 5kW).

Reply to
John Rumm

Nope, you can't use any form of pumped shower on a what is to all intents a mains feed.

A "high flow" combi will only be of any use if you have the mains supply performance to feed it[1].

Going to the expense of laying in a new feed from the street main will do nothing to increase the static pressure, but will usually improve the flow rate (i.e. less dynamic pressure drop). If you only have 1 bar static pressure then you are never going to get much of a shower from that under its own steam.

[1] You can do other complicated expensive stuff using accumulators to buffer incoming cold water which can give you a temporary boost to pressure and flow rate, but this is pretty pointless if all it lets you do is run a expensive combi solution in place of a far simpler storage system that achieves an equal result for a fraction of the cost. (Of course, for Dribble a Combi always = "better", but that is just him)

Out of date info. You will get better performance from most modern boilers if you let them drive the rads directly so that the boiler can sense the actual heating load and modulate accordingly.

Heating from the heat bank makes more sense if you want low temp feeds for under floor etc.

Standard fare for a dribble solution, it will cost more, and he has not thought it through properly.

Reply to
John Rumm

Oh indeed, but that doesn't translate into a similar saving in energy.

Reply to
Dave Plowman (News)

10 out 10. V good.

This means he is thinking. Let's wait...

You are talking out of your arse!!!!!!!!!!!!!!!!!!!!

Just don't take any notice of the idiot amateurs on here like Rumm. Coming to DIY groups can be dangerous.

Reply to
Doctor Drivel

Indeed not, some people have to install an electric inline booster heater to get a decent shower from one. Like you, for example.

Reply to
Steve Firth

The only idiot amateur here is Drivel. He's admitted as much in the past, but he "considers himself to be a semi-pro."

Reply to
Steve Firth

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