reducing flow through immersion coil

[rssteve]

ok thanks for the replys i will fit one then adjust it down if needed.

 

[mogget]

Better still - use two 2-port valves instead of a 3-port.

How would that help to balance the DHW circuit with the radiators?

edit - for some reason my computer didn't show me the last few posts, and I can't delete this message

 

[Balderdash]

Of course the reheat period on a new cylinder will be short, and being vented or unvented doesn't make any difference.

And of course you can program the DHW on/off times to suit your usage, so the effect of 'stealing' heat from the CH circuit is reduced or eliminated.

The cylinder will heat up quicker with a higher flow, if the maximum heat transfer rate hadn't been reached at the slower flow rate. It's obvious.

And as for the idea that pumping over can be solved by restricting flow through a cylinder coil, that's just deluded.

 

[oilman]

Disagree with a couple of comments by Oilman, of course it will heat up quicker if you have more flow, or slower if you restrict it, that's the whole point of balancing a system, but as above the advantages are minimal on a small domestic.

I suppose it was a bit rubbish really, but it's a matter of how much time you save for how much extra input. Since most of the water in a vented, not-high-recovery cylinder flows down the middle of the pipe coil, it doesn't get a chance to give heat to the tank before it's off spraying heat out of the return pipework.

 

[bengasman]

The whole idea of modernising your system is to have better performance.
Your new cylinder will have a recovery time of under 30 minutes and will therefore need a fair bit of heat input. It will also be well insulated resulting in a low heat loss.

The logical thing to do is to set the timer so that you never have ch and dhw on at the same time which will result in both ch and dhw reacting faster.

You should still balance both your heating system, and the cylinder to maintain a 10 - 12 degree flow return drop.

 

[oilman]

The logical thing to do is to set the timer so that you never have ch and dhw on at the same time which will result in both ch and dhw reacting faster.

Since most installers can't even be bothered to tell the customer the simplest information about the system or its controls, that is just not going to happen.