Hot water cylinder

[IMM]

The cylinder.

You should read properly. That was to make the re-heat more efficient. Other methods were given to increase the hot water volume a cylinder will produce. Duh!

[Owain]

"Christian McArdle" wrote | > A trip to the A&E at RBH is never a pleasurable experience | > at any time | > :-) | Yes, I last went when my GLW decided to squirt half a bottle of | superglue in my eye from 2m away. She was quite a good shot and | the nozzle does produce a very tightly defined stream.

Why people have to get so inventive is beyond me, if it's not in Alex Comfort don't try it :-)

| It has been completely rebuilt in the last few years, so isn't | the shabby shell it used to be.

I'm glad the eye has recovered. Have they done anything about the hospital.

Owain

[Owain]

"Christian McArdle" wrote | > > That isn't good English. | > It is. You and never are in the dictionary. | English good is this? Think so you.

"I speak English very well. I learn it from a book." (Manuel as a talking moose in Fawlty Towers.)

Owain

[Andy Hall]

Well I didn't imagine that it would be from the Yellowstone Geyser.

Please answer the question. How does having an arrangement which causes a large proporion of the cylinder contents to fall in temperature to practically cold water temperature increase the volume of available hot water?

OK, so let's summarise before you attempt to draw attention away from your confused solution any further.

1) You suggested a scheme involving two thermostats and a relay as an attempt to improve the efficiency from the boiler because it would burn for longer and hence be more efficient than running it for shorter periods. 2) I said that from tests that I did with a condensing boiler and fast recovery cylinder that I found no evidence that a scheme like this would make any notable difference to efficiency. I also said that I could see no reason why any boiler of condensing type of recent design and in the 90-91% SEDBUK category would be substantially different. I did say that I could see a reason why this approach *might* help an old fashioned cast iron boiler with natural draft flue, especially with a non fast-recovery cylinder. 3) I pointed out that implementing such a scheme with two thermostats will result in times where there is as little as a quarter of the total volume of the cylinder available as hot water. If that happens to be at a time when there is a sudden large demand for water to run a bath or shower, then that volume will exhaust quickly and the user will be left with whatever the boiler can do on an instant basis. Given the mixing effect of incoming cold water rushing into the cylinder, the results will be fairly poor. This was my point about reducing the available volume of hot water 4) You raised the point about having a flow switch to fire up the boiler the moment that hot water is used and therefore bringing the boiler on before the thermostat otherwise would. 5) You suggested that both methods together were a good idea, both improving efficiency and increasing available hot water. 6) I said that although having a flow switch does have the effect of bringing the boiler into operation earlier and was worth doing, it won't compensate for the loss of 75% of the storage capacity from the other scheme with two thermostats

In fact the effect of the flow switch, if just on the cylinder output would be to fire up the boiler each time you start drawing even small amounts of hot water, thus defeating the object of the thermostats scheme.

One way that this could be circumvented would be to only allow the flow switch to activate the boiler if both thermostats were indicating that a recovery and boiler run should happen. At this point, there is less than 25% of hot water left anyway. It is likely that the boiler won't have done enough in time to prevent the stored water being exhausted.

For most of the time, the lower thermostat will be calling demand and the upper one not and there is no way to know with a simple thermostat arrangement like this whether there is 25% or 75% of HW left and therefore whether the boiler should be fired up when water is drawn. This could be handled by having separate plumbing runs for the bath and shower and having the flow to those monitored. Otherwise the arrangement will be worse overall than just having a single thermostat with its hysteresis. You will fire up the boiler, every time the hot tap runs at all, whcih is precisely what you didn't want to happen because it's less efficient (or so you say).

I don't think you thought through the implications of your solution before suggesting it.

[IMM]

Read the thread all again from the beginning.

Read the thread all again from the beginning.

Which of course in nonsense.

You don't read. I said on the highest flow taps, bath/shower.

Read the thread all again from the beginning.

[Andy Hall]

No just answer the question.

No, I made the measurements and did two runs of each test. The results were consistent to about 2% as I said.

Ah, so it requires a replumb of the house to make it work.

That isn't necessary. By avoiding the issues, you've answered my questions.

[IMM]

All is there. I'm not going around the mulberry bush.

Read again. This is for your own good.

[Andy Hall]

Something's there - it's simply conflicting and inaccurate.

No, it's OK, thanks, the situation is completely clear.

[IMM]

You can't read.

Keep up the reading, it may become clear.