Heat banks (again!)

[Pete C]

Hi,

Just a general point, I wonder if it would be better to run the radiator return through the heatbank lower coil, with a pipestat and bypass valve across it.

Then as the return temperature from the radiator rises, the valve would open so excess heat is dumped into the heat bank, reducing the flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until the boiler cuts out but the heat stored in the lower part of the heat bank would help keep the radiators hot and delay the time until the boiler fires again.

There's probably some more potential in this idea if I could think of it :)

cheers, Pete.

[IMM]

< sniuo >

You have not a clue.

Yes. I said that many posts ago. You can't read.

No. Each section of the heat abnk has its own controls.

You turkey I am not about an expensive modulating boiler - for about the

50th time. You are hard of thinking. < snip >

You really do not understand. It is pointless going on with you.

[IMM]

< snip >

[IMM]

Well it must be 7.

The point is boiler cycling. Not mains pressure water to charge the thing up.

< snip >

Not worth it; a confused man.

[IMM]

The rads directly off the heat bank. The return of the rads runs through a plate heat exchanger and then back to the heat bank. The return from the heat bank back to the boiler runs through the plate heat exchanger. The returning rad water would cool the returning boiler water lower the temperature. They may be case where this may not occur, but these occurrences would be few and far between.

[Andy Hall]

You were not at all clear. Would you like me to quote the piece in your post.?

This is a completely pointless and overcomplicating exercise.

The conclusion was around a modulating boiler several posts before you introduced this wild goose chase.

.andy

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[Andy Hall]

This gets more and more stupid. Now you are adding an additional heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it all.

.andy

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[IMM]

You clearely do not understand.

You clearely do not understand.

No! You were on about a modulating boiler, no one else.

[IMM]

You clearely do not understand.

About the only sensible thing you have said.

[Pete C]

Hi,

I might be getting mixed up with a thermal store. The rads would be connected directly to the boiler and return through the lower coil of the cylinder. Basically the lower half of the cylinder would act as a buffer to reduce cycling when central heating demand is low.

cheers, Pete.

[Pete C]

BTW do all condensing boilers modulate right down, or do some just have two output levels for DHW or CH?

cheers, Pete.

[IMM]

So a normal direct rads from boiler and a quick recovery cylinder with an extra coil at the bottom?

I could improve matters. You are using the bottom half of a cylinder as a hot water store to prevent boiler cycling. May as well sue a proper heat bank/thermal store. It will lower the rads return temperature going back to the boiler, but how much is well ..err...not known. My gut feeling is not by much. Then you have a stat and a 2-port valve as well and the extra expense of the coil in the bottom of the cylinder. A plate heat exchanger is passive and will drop the return temperature quite sharply

[IMM]

Either you are laughing at the notions of an amateur, which was good advise if the mains water pipes are run under a conservatory floor gaining heat from the sun, or have lost the plot.

None modulate right down to zero. I think the best of them goes to about 5 kW

None have two outputs as such. One has two boiler run stats to give CH and DHW, but only when using a priority system; when DHW calls, a diverter valve diverts all the boilers heat to the cylinder at the temp the DHW stat is set at.

[Andy Hall]

Most reasonable ones modulate over at least a 3:1 range, some as much as 8 or 10:1

Some also have different behaviour when they are told (via an electrical input) that they are driving CH or driving DHW.

.andy

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[Andy Hall]

Mine goes down to 3kW.

Or with multiple zone valves and detection as to whether the CH or DHW is being driven.

.andy

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[Andy Hall]

That's certainly true. Would you like me to tell you how?

.andy

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[Andy Hall]

From the OP, (and I quote):

"It looks like the answer is a Worcester Greenstar running vented into a direct heatbank with a zone valve for the rads and a second zone valve for the towel rails and airing cupboard rad."

Now let me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it says that the output to central heating is from 7.4 to 28.8kW. This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

.andy

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[IMM]

W-B tech people say the "heating" boiler can deliver a constant temp. I know I have recently put one in and used a late heat exchanger on the red return to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.

[Andy Hall]

I am sure it *can*, but why screw up a perfectly good and efficient modulating boiler and wreck its efficiency?

Where did you install this claimed boiler?

I think that you are making this up as you go along......

.andy

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[IMM]

The makers do not seem to think it is inefficient at all.

Relatives house, keeping the old boiler as a backup in case the B-W fails. They just flick a switch to bring in the old clunker and light its pilot.

I don't copy you thank you. Keep your dirty habits to yourself.