Worcester 24i Combi - water too hot

alcart · 29 Sep 2007

We have a 9 year old boiler which from the 1st day gave very hot water (scalding temp) at full flow but flow rate is =>30% of normal flow.

I know it's not furring up because nothing has changed since installation.

I would like flow of water to increase there by cooling the tempurature down - but when there is only 1 dial for Radiator temp and a pressure gauge, how do I do it?
Any ideas anyone?
Thanks

Agile · 30 Sep 2007

Your boiler IS scaled up and thats compounding the problem by reducing the flow and increasing the temperature causing more scaling.

The DHW part will need descaling!

Tony

alcart · 30 Sep 2007

Thank you for for reply but as I said, there is no difference between now and the first day of installation of the new boiler, in temperature/flow.

The other thing I ommitted to mention is that because we are running with micro-bore pipes on the C/H, I insisted that an

in line

descaling unit be fitted to the water inlet.

simond · 30 Sep 2007

Where are your flow rate readings to corroborate you have the perfect 9yr old plate heat exchanger?

How many litres per min are you getting out of your combi (at excessive temperature)?

Has it not occured to you that 24Kw of energy can only produce a maximum amount of temp rise for the specific latent heat value of water?

If your boiler is delivering more heat you must have a restricted flow, and here you should start looking at the domestic hex or your scale reducer, or even the incoming main and associated pipework.

Or Worcester have unwittingly chosen you to road test their 1998 perpetual motion machine.

alcart · 30 Sep 2007

How many litres per min are you getting out of your combi (at excessive temperature)?

I can tell you that at full flow 1ltr = 18 secs and that before it was fitted, flow rate was not an issue ie pipe work upto boiler should not be the issue and lets assume that pipe work from the boiler is also OK.

Afterall it was fitted by qualified engineers

Is there an easy solution possible - I'm thinking for eg. remove bottom panel and turn screw a 1/4 turn - increases water flow through boiler.
In fact lets assume that the boiler is new has just been fitted and the engineer's just gone - 1ltr=18 secs

bobthebender · 30 Sep 2007

1ltr in 18 secs is carp and should be more like 2.5 ltrs on this boiler ?

Agile · 30 Sep 2007

alcart said:
Afterall it was fitted by qualified engineers

More likely qualified cowboys!

Your boiler should give 9 litres per minute at about 42 C if the inlet temperature is about 7 c.

Why are you so reluctant to accept that your boiler is faulty?

What did you mean by """We have a 9 year old boiler which from the 1st day gave very hot water (scalding temp) at full flow but flow rate is =>30% of normal flow. """

To me that means the flow rate is only 30% or less of the "full" flow rate. Thats what your 3 litres/minute is !

Tony

alcart · 1 Oct 2007

Can some one describe what the Domestic Hex is, how it works and is it easily replaced?

Agile · 1 Oct 2007

Your boiler should give 9 litres per minute at about 42 C if the inlet temperature is about 7 c.

Why are you so reluctant to accept that your boiler is faulty?

What did you mean by """We have a 9 year old boiler which from the 1st day gave very hot water (scalding temp) at full flow but flow rate is =>30% of normal flow. """

To me that means the flow rate is only 30% or less of the "full" flow rate. Thats what your 3 litres/minute is !

Tony

alcart · 1 Oct 2007

Tthe flow rate IS one litre every 18 seconds and I am not saying there is nothing wrong with it, but all I want to know is -
"Is there a way of easily increasing water flow through the boiler" (if we assume the boiler itself is restricting the water flow)?

And the answer is ......?
If yes - and this is how to do it......
please

scatmanjohn · 1 Oct 2007

How long has a worcester 24i had a plate heat exchanger.

Come on fellas.

There is no way of adjusting the hot water temperature, its preset. IMHO

Does the water come out of the cold tap much faster than the hot tap?

If "No" than your not going to get any more flow through the boiler to the hot taps.

If "yes" then you have a restriction somewhere (the boiler will reduce it a bit)

Softus · 1 Oct 2007

scatmanjohn said:
How long has a worcester 24i had a plate heat exchanger.

Eh?

Gasguru · 1 Oct 2007

Bithermal heat ex.

Perhaps the mains pressure is poor....has anyone removed the flow limiter in the boiler?

Agile · 2 Oct 2007

His hot water temp is too high and has deposited lime scale on the DHW heat exchanger and slowed the flow down.

Needs to be replaced or cleaned.

As its overheating its most likely the temperature control is faulty or it has been used with a restricted flow rate for too long.

Tony

alcart · 2 Oct 2007

Agile said:
His hot water temp is too high and has deposited lime scale on the DHW heat exchanger and slowed the flow down. Tony

To reiterate - The Flow rate is the same today as when it was fitted 9 years ago, it has not reduced. It has also been serviced every year.

To clarify - the boiler I think has a grey lower panel with a rotary dial for radiator tempurature on the LHS and a pressure gauge RHS - no other dials/switches/etc.

So what I gather so far, is a flow limiter maybe responsible and as for cold water flow - is as good as avg users expect ie infinitely better than hot.
I appreciate all the replies - Thank you all so far!

diynot

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Worcester 24i Combi - water too hot

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