On 5/20/2017 1:35 PM, Terry Casey wrote:
I note it says in the wiki that: "I need a new one, what should I get!" comes
up in some form almost every day on uk.d-i-y, but couldn't find enough
information to clench the deal, one way or the other.

My wife and I are living in a two bedroomed bungalow - there's nobody else
living there except the cat! The central heating is old - if the pencilled
date on the back of the controller I replaced recently is anything to go by
it dates from 1996.

We had a quote recently from a local plumber who advocated a combi - which
I've always been convinced from various things I've read (probably here) that
they can be problematic - but he said that modern combis are much better than
their predecessors and would be highly suited to our needs. He also pointed
out that he has a combi in his 4 bedroom property and has no problems with
it.

We then got another quote from someone who is clearly prejudiced against
combis! Apart from additional strain on the old pipework - which we are well
aware of - he said that the increased pressure can damage the non-return
valve in dual fill washing machines (ours is currently a dual-fill Hotpoint)
but that we wouldn't be able to run hot water from two taps at the same time!

This could be a worry if we couldn't wash our hands (or whatever) every time
the washing machine was filling or the other is running a bath. Can this
really be true?

Quote No. 1 includes an Ideal Logic+ 30kW boiler whilst No. 2 is for a
Worcester Bosch 15ri boiler. No. 1 includes quotes for both combi and non
combi options (but does give any indication of which non-combi boiler would
be fitted) and No. 2, as might be expected, doesn't have a second option!

How do these boilers compare - assume No. 1 would use a non-combi version of
the same boiler?

All comments gratefully received!

Terry


I sometimes use a small holiday cottage on the Isle of Wight which has a
combi that seems to do the job: enough hot water for a shower, sink
water hot enough for washing up properly, and the CH is OK too.

HOWEVER, I've had two combis in my admittedly larger and sprawling 18th
Century cottage and they were both hopeless. Apart from generally
inadequate hot water not particularly good heating, they were not reliable.

I ended up putting a separate electrically heated cylinder for DHW.

More recently I replaced the lot with a traditional "system" boiler
(Vaillant) and a new unpressurised hot water cylinder but the same
radiators. Finally I have enough heat and water from gas. I do have a
Stuart Turner double pump for the shower, and a second Stuart Turner
"single" for the DHW, which gives me a decent flow rate particularly for
the bath. A shower pump is certainly not a bad idea if you don't have
much head.

I know TNP has good arguments for pressurised hot water, and if I was
starting from scratch with an unlimited budget this is probably what I
would do. But it comes at a price, and may need more servicing.

I would personally only consider Vaillant and Worcester Bosch, on the
basis of advice both here and in Which?

As you have probably surmised, the anti-combi guy is probably a bit of a
bull****ter, but what he says about hot water flow rates is reasonable.

I guess a "system" installation with a separate hot cylinder is going to
be a bit more expensive.

How old is the bungalow, and what's the insulation and draft-proofing
like? Semi or detached? There are calculators on-line to help estimate
your heating requirements which could vary by a factor of 2. Or if you
are on an estate, ask your neighbours what boilers they have, and
whether they are adequate.