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I have a problem with not being to run a bath quickly using my combi boiler, as the water runs cold intermittently. I was advise to read up on hard water.

Having done that I have consulted a local heating engineer and plumber, whose initial over phone comment was that the boiler was likely under rated for the house/users. Only my wife and are are in a 3 bed linked detached.

As well as water the unit has to serve:

2x26" double radiators; 2x33" doubles; 1x63" single; 1x44" single;
1x26" low level that goes under kitchen breakfast corner. double will grille on top; hated towel airer 600x1150 mm. Inch sizes are approximate.

May I have opinions on the adequacy of the set up, and if a power flsuh and de-scale will much alleviate the problem, there being £1700 difference in cost?

Hi,

The hot water requirements is the way good installers match a boiler to a client.Which boiler do you have and what is its output for HW in litres/minute?

If your bathroom is quite a distance from the boiler then you could slow the rate you fill a bath and see the result.

De sludgeing/ scale removing could help if heat ex is scaled up, but not at that price -- shop around.

Steve

Make and model of boiler?

Most heat the water within the main heat exchanger and sludge is unlikely to be the cause if this is the case - is the boiler noisy?

One possibility is that the pump is not running on DHW.

Obviously a competent boiler engineer would check the temperature sensors, flow rates and do a thermal survey to assist with diagnosing the cause of your problem.

[quote="Steve the gas"]Hi,

The hot water requirements is the way good installers match a boiler to a client.Which boiler do you have and what is its output for HW in litres/minute?

If your bathroom is quite a distance from the boiler then you could slow the rate you fill a bath and see the result.

De sludgeing/ scale removing could help if heat ex is scaled up, but not at that price -- shop around.

Steve[/quote]

The boiler is a Protherm 80e

Flow rate @ 30 deg C temperature rise ….11.2 l/min
@35…………………………… 9.6 l/min
Minimum water flow……………………….2 l/min
Max/min supply pressure……………………6/1 bar
Full technical details are at

http://www.postimage.org/image.php?v=gx1mujcr

The bathroom is immediately above the kitchen, where the combi is located, so in theory it is quite close to the boiler. As I said in the OP, I can get bath hot water only if the hot tap is turned no more than about 10 deg: more than that the water runs alternately hot and cold until eventually at full aperture the flow is more or less cold.

I did not actually quote a price for the power flush and descale. For clarity the power flush and descale quote was £450 and a new boiler £2185 inclusive of VAT and the foregoing. BTW I live in S.W Hants, where prices do tend to be high




[quote="nitro23456"]Make and model of boiler?

Most heat the water within the main heat exchanger and sludge is unlikely to be the cause if this is the case - is the boiler noisy?

One possibility is that the pump is not running on DHW.

Obviously a competent boiler engineer would check the temperature sensors, flow rates and do a thermal survey to assist with diagnosing the cause of your problem.[/quote]

Noisy? If you mean clunks and grunts, then I’d say it was not, but it does roar, We can hear it sitting out in the garden

Not ruining on DHW? Is there a quick way to tell?
:)

A bit :cry: sad that no more replies received following my last post.