Combi boiler - Hot water 'heat dump' too hot

Yes,why oh why do combi installers chuck out a perfectly usable cylinder,especially in large family houses?. My view for family properties is to keep the cylinder,feed it from the combi,obviously make sure things are well insulated/controlled.

This that is your view you should change it, as the cylinder will burst. Find how water systems work. here are high flow combi's around, that will do a large family.

An advantage of a combi is that it liberates space tanks and cylinders take up.

Have you ever though about taking remedial English lessons?

Have you ever thought about taking remedial English lessons?

No need to as I am brilliant at English and life in general.

Strange. I know of one system where the combi heats a tank in the normal way, and the water heating side is used just for the kitchen. Not sure what the benefits are, as the owner is as mad as you.

And the cost to achieve this, assuming a good storage system already exists?

Not everyone lives in a rabbit hutch.

As well as weird effects due to the combi design, another possibility if the combi DHW output and the CH pipes run in very close proximity (particularly if boxed in) is that the DHW is being heated by the CH pipes whilst sitting adjacent to them, to a much higher temp that the actual DHW output. When you turn on the tap, this slug of hot water comes out.

It is only a suggestion, and probably isn't the problem, but could be fixed by separating the pipes with a bit of insulation.

Christian.

The evidence for that seems to be a little thin on the ground...

It can be good in a large house to reduce water lead times, particularly if the boiler is in the kitchen. The hot water cylinder is placed near the bathroom to provide lots of hot water quickly, whilst the kitchen runs off the combi, because you'd have to draw off 10 litres of water before anything came through from the distant bathroom. It also provides drinking hot water in the kitchen, which is very useful when cooking. I use my hot tap all the time to fill kettles and pans. (It's a heat bank, not a combi, but still drinking water).

Christian.

Please do not comment on fields you have no experience of.

Should we award the same respect to your other posts as we do to the one above?

How about attempting top answer the actual original question?

Phil The uk.d-i-y FAQ is at

combi,obviously

It was answered. It will burst.

I doubt you would recognise a good post from a bad one.

Short term memory propblem again? go read the OP again.

I installed a similar system for my nieghbours directly opposite my house. S-plan for the house, combi HW for a sink in the garage below the house. They like baths and it would have been hard to gain access to the HW pipes under the kitchen floor to supply the garage sink.

The cost IMHO is less significant the space taken up in the kitchen (usually). The space to be lost in the kitchen would usually be more precious than the space gain in the loft and/or airing cupboard.

Round here a lot do.

Right. Suppose it makes some sense. Any combi should be ok for just the kitchen tap. Could it still be used if the central heating side was drained down for any reason?

IME experience there are several reasons why (ordinary) combi boilers have poor regulation of DHW temperature.

but mainly:

1. Can be mitigated by good design and practice. Namely don't fit a combi where the supply is inadequate. Take it's supply upstream of other draw offs (even consider putting a slight restriction on the feed to everything except the combi.
2. This is not a common problem and shoudl be mitigated by getting 1 and 3 right.
3. Descale or replace secondary heat exchanger.