Hold and cold bathing!!!

oldwiring

We have trouble running a bath. For a while the water runs hot, the cold, then hot again and so on. The result is that we never get a really warm one. However the shower unit ( over the bath, but not one of those bath mixer things) seems to run hotter. It's a Bristan Thermostatic BTW. Water is heated by a combi sited in the kitchen below.

What should we look for to solve the problem? I like a good soak:D.

oldwiring

No ideas or clues then?

Bungarm2001

Could be a number of things. For instance, the temperature could be intermittent due to varying pressure in the flow?

What I mean is, do you have any other appliances running at the same time as the taps, like a washer? Your boiler might not be able to cope with providing hot water for more than one thing at time.

Could be something simple like the tap washers are faulty. How old is the boiler/taps etc? Have you had the boiler serviced regularly?

Canucklehead

Hi
How long has it been doing this?
Can you see the main burner in the boiler ? Does the flame remain constant or rise up and down while you fill the bath.
Might be a secondary heat exchanger blocking.
Do you fill the bath by a mixer tap?

Corgi Guy.

oldwiring

Sorry for delay in reply. Here are the bath filler and the shower unit
http://docs.google.com/Doc?id=ddzzpk66_13dtv2993m
Adjacent to the bath is the bowl, which has a basin mixer, and the opposite wall to that a towel airer. The bathroom was renewed in the last year. Immedaitely belw is the kitchen with its sink unit with mixer tap. The boiler is a Protherm 80E aged about5 1/2 yrs. It suppliescentral heathing plus hot water as above, and also occasionally to the utility room and small toilet. It is serviced.

The problem has been quite recent and by experiment I've found that better, adequate rather than good that is, hot water to the bath can be got by a very slow fill!

I hope alll that helps. I am wondering if it could have to do with a CH radiator that had to be taken off and refixed, as the trouble has been noticeable since then, However I would not know, if it had prededed that, but had not been as bad as we would have noticed.

PS Just did a test re

Can you see the main burner in the boiler ? Does the flame remain constant or rise up and down while you fill the bath.

. The boiler has a very small peep hole, so what OH could see while I was running the water may not be relevant. She said that several times the flame appeared to go out and then come on with a whoomph. I probably ran it for less than 5 minutes.

Boilercare

I would be inclined to agree with Canucklehead on this one.
The most common cause of this type of symptom is a partially restricted (dirty) secondary heat exchanger, although a failing temperature probe in the boiler (called a thermistor) can also result in similar symptoms too.

A good service engineer can usually clear the heat exchanger to some degree without having to replace it. However, this is merely a stop-gap repair because until the route cause of the problem is identified treated, it will return.

The most probable cause of this will be due to the central heating system being contaminated with dirt and will require chemically cleaning (powerflushing is the most effective way to do this).

Regards
Dave

oldwiring

How much is the going rate for that? I live between Bournemouth and Southampton.
As the boiler is a combi, do I need to use a 'specialist' servicer in them for the flushing?
We also have extremely hard water. Could that be an additional factor?

Isn't power flushing something that is done to CHtg radiators and pipes? I thought the water supply to a combi came direct from the mains, so ask how does doing something with CHtg help?Is I'm inquisitive.

S-i-L found that if the kitchen tap ( adjacent to boiler) was turned completely to hot but only on at just above a trickle, the boiler temp indicator shot up to 60 +/- say 2 deg. As soon as full on it dropped to around 30.

Further comment?

oldwiring

Bump Still hoping for comments out of my last post.

plumb1_2

oldwiring wrote: »

We also have extremely hard water. Could that be an additional factor?

Isn't power flushing something that is done to CHtg radiators and pipes? I thought the water supply to a combi came direct from the mains, so ask how does doing something with CHtg help?Is I'm inquisitive.

The heat exchanger can be descaled by powerflushing.Also advise fitting a combi-mate.

jennifernil

What is a combi-mate?

Plumbers_Shop_Lee

To answer Oldwiring's question first, the combi heats water taken directly from the cold main supply by means of a heat exchanger which has two seperate sets of waterways one set carries the cold water and the other side has the heating water passing through it. The heat is transferred across from one side to the other giving you hot water.

And secondly all the info you need on combimate can be found here http://www.cistermiser.co.uk/products/combi.shtm