Thermal Store (DPS), UFH, Multi Zone

[the-moog]

Dr Evil / Andy Hall.

I seem to have caused a bit of a storm with this one!!

Rather than dealing with hypothetical situations, lets deal wit actualities. Perhaps that way I can add something to the argument tha solves the riddle.

The Boiler WILL be a Condensing boiler, a Vaillent EcoMAX635E. Partl because this boiler is available under the local council money bac scheme, but also because its one of two that meet the power outpu requirements for a low enough install cost.

The existing house is very lossy, its old and looses a lot of heat. W won't install injected cavity insulation as all the similar houses i the area that have had that done now have major damp problems. Thoug we are replacing the loft insulation.

We WILL have to use UFH as there is no room in at least three space for radiators.

I don't know if the UFH will run of the radiator circuit, but I expec it will.

At least one of the UFH circuits will have to be on its own zone as it a conservatory and may require independent heating.

Other spaces (three bedrooms) may run off UFH if its suitable otherwise these spaces and the rest of the house, will run of radiators. It would be impossible to install wet UFH on the groun floor without digging out a LOT of soil.

The final and main reason for the heat store is to allow mains pressur hot water without using a combi as combis always suffer from sever temperature drop as the flow rate increases.

If I side with Andy, then it seems I need to run the radiators off th boiler, together with any UFH zones that are connected to CH circuit and the conventional UFH and HW off the thermal store, this seems t mean two separate S plan heating systems.

If I side with Dr Evil, then it looks much simpler; a manifold on an plan direct from the store with as many zones as I can afford.

Is there a sensible solution?

Jason

-- the-moog

[Doctor Evil]

You are grasping it. Well that boiler is suited to a heat bank/thermal store. It doesn't modulate down that low.

There are thermal store/heat banks available with three temperature zones. The top half for DHW, the centre section for rads and the bottom lower temp section for UFH. The UFH can be on a manifold fed from the store with 2-port valves on it for the zones. This simplifies matters as everything is off the one store of water. Cylinder stratification will give high temps at the top and low temps at the bottom, exactly where you need it.

Try:

(make square stirage vessels) (make heat banks and storage vessels to size) (make thermal stores and stioarge vessels) (make cylindrical heat banks and storage vessels. Will make to order) (make heat banks and storage vessels) (make cylindrical thermal stores and storage vessels. (They are quite cheap and will make to order) make cylindrical thermal stores and storage vessels (make cylindrical thermal stores) _________________________________________ Usenet Zone Free Binaries Usenet Server More than 120,000 groups Unlimited download to open account

[Christian McArdle]

There is unlikely to be significant difference in performance between the systems. The main benefit of running the rads off the heat bank is that it allows direct operation, which allows you to run with a lower flow temperature. However, it may defeat any load compensation operation in the boiler.

Both systems will be efficient. Running the rads (and presumably the UFH as well) off the boiler will work best if the boiler can be programmed to have a higher flow temperature when heating the heat bank and to drop the flow temp (or use flow compensation) when running the rad zones. This might require more complicated controls, though, and may not be supported by the boiler at all.

Note that if you choose direct operation, you need to choose a boiler capable of running open vented. I don't know if the Vaillant supports this. The Bosch Worcester Greenstar 29HE "Heating", does.

Christian.

[Christian McArdle]

Possibly poor choice of materials. There are lots of different products, some of which may cause this problem, whilst others avoid it.

Note that the energy efficiency of conservatories, coupled with the maximum output of underfloor heating means that it is not usually possible to use underfloor as the sole source of heating, whilst maintaining the ability to get a 24C temp rise (-3C to 21C). This means that either the conservatory won't heat entirely during exceptionally cold weather, or additional auxilliary heating must be provided.

Christian.

[Doctor Evil]

I don't think there is ant load compensation control in the boiler. I think it modulates to maintain a flow temp. Not 100% sure.

Some heart banks have a long thin arrangement, so that the lower part is around 50-55C for UFH. The stratification mean that the top will be around

75C

The Glow Worm is similar.

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[Andy Hall]

Yes it will, quite happily through a blending valve arrangement - standard products.

You would need to do that anyway.

This is the reason for a store, a good idea and completely independent of the heating requirement.

You don't really need to "side" with anybody. I really don't mind. I've explained the scenario where it is of little value and less efficient to run the heating circuits from a store. In my view, your scenario fits right into it because a) you are choosing a modulating and condensing boiler able to go down to quite low output and b) because of your high heat losses from the house, there will be more days of the year during which you will need an output from the boiler greater than its minimum.

Given your situation, my view is that the correct design is to run the heating circuits directly from the boiler for efficiency reasons. Whichever way you went, you would need the S plan control arrangements so there is little difference from the control perspective.

I've explained the scenarios for the boiler and why it operates more efficiently when operated continuously at low power as opposed to bursts of higher power.

I'm certainly not going to get into a debate with Dr Drivel about it because the discussion gets obfuscated and goal posts moved until everybody is confused, most of all Dr Drivel - a pointless waste of everybody's time and energy.

[Doctor Evil]

Andy, you are not in the heating business, like myself. You are merely guessing. A bad guess at that.

Please understand the different types of boiler modulation control. I have explained it.

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[Andy Hall]

Plastic pipe fitting?

I don't make guesses, I look at the information. I also look at the engineering and physics.

I avoid bringing irrelevancies into the discussion in order to confuse and attempt to obfuscate the real issues.

I am fully aware of the different types of modulation control, thanks.

[Doctor Evil]

You are an amature idiot. Please do not give advise on matters you have no personal exdperinece whatsoever, a man is wanting firm advise not scatterbrain babble. Another Frank Spencer.

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[John Rumm]

Oddly enough you haven't... Would you care to?

[Andy Hall]

Motoring on again?

I'd always understood that you were the master of scatterbrain babble. Certainly that's what the record shows.....

[Andy Hall]

This should be fun :-)

[Roger]

The message from John Rumm contains these words:

If DrivEl does rise to the challenge I trust someone will post the url of the site he copied and pasted his explanation from. :-)

[snip drivel]

A silly pos

-- snip drivel

[snip drivel]

I agree with this

-- snip drivel

[Doctor Evil]

Oddly enough I have. Read back on the thread.

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[Doctor Evil]

....and our master technical brain interjects.....with...well..not worth it...

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[Doctor Evil]

Frank, stop pretending to be an extpert in field you no background whatsoever.

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[Doctor Evil]

Frank, it was, as it is already there. It is clear you didn't understand.

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[.]

In article , Doctor Evil writes

Another post from John, what an armature!