Mixing header and pumps

[IMM]

No. I don't want their advise on anything except the boiler. Outside the boiler they are out of their depths.

Well...

On Venus eh. A right space cadet.

[John Aston]

Thanks, Andy, for your considered analysis.

As discussed, I'd like to modulate the water temperature through the radiators to reflect the outside temperature. A modulating boiler seemed an obvious choice in this respect.

But my worry about using a MAN (or Viessmann or other) modulating boiler is that the manufacturers require the installation of a low loss header to smooth out the boiler flow rate. It seems odd to me that a three foot tube of pipe shunting the boiler flow/return can be as thermally efficient as piping the heat directly through the rads/UFH.

Presumably you don't have this issue, because you don't need circulation pumps to get the water round your heating system. I can see the manufacturer's point that such a pump in series with the primary flow would screw up the boiler's attempt to control its flow rate.

I had the same concern. Unfortunately, GAH won't sell the accumulator without their Ariston cylinder. Unless I can find a simple alternative way of boosting the cold supply, I can't use the heatbank.

[IMM]

When the heat bank is sectioned off it does. You have been told this.

The 25C is the delta T they recommend, which is different to the temperature rise. You will find that boiler of 15kW and 32kW may have a 25C delta T. Common sense says that the 32kW will raise the temp higher with the same flow rate through the boiler.

What tripe.

But will.

Pushed though a narrow pipe. A heat bank hold a large mass of water.

The incomplete thoughts of an inexperienced mid. Andy, you no experience of UFH whatsoever. Now stop making things up.

Tripe again. Most are reduced in pressure to around 2 to 3.5 bat.

You can also de-scale the plate easily enough by removing it. You can also increase the flowate by adding a plate. Very flexible.

[Andy Hall]

You might want to contact their technical departments in Germany on this point.

I suspect that this could be the reason. The pump in the MAN boiler is adequate to deliver its flow requirements.

I wonder whether another solution might be to use plate heat exchangers. I've used one of these to run the circuit for my workshop. The main reason was to isolate it from the house system - it was a belt and braces in case of damage or freezing (although I do have antifreeze in the workshop circuit. When the workshop demands heat, the thermostat operates a pump in the workshop. A flow switch in the house opens a motorised valve to the primary side of the heat exchanger and that creates a demand signal to the boiler. In effect, the exchanger is treated like an additional CH zone.

I've monitored the boiler behaviour when the house CH is on and not the workshop, the other way round and both. Both work well and the boiler continues to do its stuff to control the water temperatures correctly.

It struck me that this was not dissimilar in concept to what you had in mind, although I would get comments from the vendors on it. The heat exchangers are cheap enough at less than or around £100.

Hmmm.... Aren't there other accumulator suppliers?

[Andy Hall]

Sectioned off with what?

It is what the boiler heat exchanger will do.. Are you saying that a

50 degree dT is standard operational behaviour?

Yes it is, to suggest that this kind of product does all these things under the conditions envisaged.

It doesn't matter at those power levels. It does at 30kW which is the intended application for a thermal store with boilers that don't modulate.

It doesn't matter at this power level, or frankly any other as long as the pipes leading to the load are adequate to carry the flow.

Does a floor have thermal mass?

I am talking about flow at the operating pressure. I know that you have difficulty in differentiating the two concepts.

A water softener is to be used here - undoubtedly a proper one.

Provided that the mains will deliver it.

[John Aston]

Andy, I assume that the "near setpoint" control is because you have a DHW temperature sensor rather than a cylinder thermostat? May I ask what kind of cylinder you have? I can't find any cylinder manufacturers that provide a sensor option.

[IMM]

baths/showers

I give up with this one. A non-government owned section. That better for you?

Read again.

It does. When a system is up to temp small drops in flow temp can cause irritating cycling.

I give up again. Is it worth it?

Depending on the type of floor.

If a mains pipe is 6 bar and an excelent flow and you have a reducer to 3 bar, you will not get "a flow rate of whatever the mains will deliver".

No need. A waste of money. A good phosphor descaler is all that is required. I know you paid a fortune buying one not know what was on the market.

Is the pope Catholic? Is the Queen ripping us off?

[IMM]

Stem Sensors usually use the same pocket as stem stats.

[Andy Hall]

Probably better before you dig yourself into a deeper hole.

Please answer the question directly.

The temperature is low - around 40 degrees flow at this point by definition so it doesn't matter. The boiler controller introduces hysteresis to avoid the burner cycling anyway - all very simply achieved.

I would if I were you

You may well get less. However, you do need to learn that pressure and flow are quite different things even though they can be related.

The salt consumed is easily offset by detergent savings which are not achieved with phosphor descaling. The capital cost is amortised over

20 years minimum, so even a top of the line softener costing £750 costs approximately £3 a month in depreciation. I think that I can run to that and many other people can as well. Perhaps you should ask Santa to bring you one for Christmas.

The poor old guy isn't much of anything any more.

Definitely not. Last time I spoke to her about it she asked after you and wanted to know if you'd be interested in collecting rents for her various country estates.

[Andy Hall]

I ordered a sensor pocket to be fitted to the side of the cylinder which is a fast recovery type. I ordered a model suitable for pressurised use so that if I ever decide to have the water pipe from the road upgraded I could switch to this. Since this would involved ripping up the drive, I would not consider it until the drive is redone at some point.

Basically, the pocket is a blind tube with fitting that goes into the cylinder. The sensor was an extra component but was not very much (£15 IIRC) and is a brass tube with embedded semiconductor sensor. This is a gentle interference fit into the pocket and ends up at about the radial centre of the cylinder. It is then wired back to the boiler. There is a function choice on the boiler to tell it that the input is a sensor rather than a switched thermostat. The boiler then operates on the basis of sensed temperature and also displays it along with flow and return water temperatures, outside temperature, pump output and fan speed (equates to burner rate.) The whole behaviour can be logged on a PC and it's possible to see the entire boiler behaviour with values graphed and tabulated

[The Natural Philosopher]

Give up Andy. IMM is a 'conviction' plumber.

He doesn't understand logical reasoning, the laws of physics or cost benefit analysis.

Its easier for simple minds to believe in things with unswerving loyalty. Look at his politics.

[The Natural Philosopher]

dunno mate. I live in snotty england. You are the one in Middle england.

[Andy Hall]

Ah...... Do you think he learned it inside? Could explain the use of the hacksaw.

I do see what you mean......

[John Rumm]

it's OK, I am sure Andy can read without you praying to him as well...

[IMM]

baths/showers

My God look at what the snot said.

[IMM]

You really haven't much of a clue. He goes on...

They can happen. It depends on how the heat bank is arranged. Now as usuall he goes on about justification for buying an expensive product, like a stuck record.....

< snip. Same boring non-comprehension >

Das but true.

[Andy Hall]

So explain precisely how this miracle of science is achieved.....

So please explain exactly how it is arranged to achieve all of these things.

[IMM]

Just read properly. It has all been explained.

Just read properly. It has all been explained.

[Andy Hall]

No it hasn't as you know full well. OK, that's fine. Clearly you don't know so we can leave it there.

As above.

[IMM]

How is the third world today.