11 pints of water

[Mr_GWP]

Hi,
Recently noticed that it takes approximately 11 pints of cold water to come through until we get luke warm water out of the hot tap. This happens on Kitchen tap and both the Shower room and the bathroom. Baxi engineer has been out 4 times and said all is normal but said he would change the Heat Exchanger as a precaution. My water bill has nearly doubled in 18 months and to be honest its got the point that we are looking at having a new boiler installed.

 

[Mr_GWP]

Hi,
Recently noticed that it takes approximately 11 pints of cold water to come through until we get luke warm water out of the hot tap. This happens on Kitchen tap and both the Shower room and the bathroom. Baxi engineer has been out 4 times and said all is normal but said he would change the Heat Exchanger as a precaution. My water bill has nearly doubled in 18 months and to be honest its got the point that we are looking at having a new boiler installed.

I forgot to mention that this is from the boiler being warm too and was tested on one occasion. This happens on every occasion and is worse in the mornings.

 

[John.g]

Turn off the cold mains supply at the Combi, open the hot tap, no water should flow.

 

[snowhead]

As John is suggesting, or will be, there may an issue that is not the boiler.
A new boiler may not fix it.

Have any changes been made to the plumbing immediately prior to the issue starting?

How far away from the kitchen or bathroom is the boiler?
Does the hot pipework from the boiler run through any particularly cold areas of the house?

 

[Mr_GWP]

Basically the combi has been installed in the garage and has replaced a traditional system with the cold water tank and hot water cylinder. The combi was installed 15 years ago has a what you guys call a loop in the airing cupboard. I know the water has to travel further but up until 18 months ago worked perfectly.. But has sort of lost its performance. It has been recommended to me to either have a boiler fitted with a pre heat function or go to a 'System' type system.. Not sure what to do. A couple of installers have recommended a 35 - 40kw Worcester/Bosch with a pre heat. Our current boiler is a Baxi 105he 30kw with no pre heat..

 

[John.g]

A 30kw combi will flow 12 LPM with a 35C temperature rise so you should get a temperature of 50C (very hot) assuming the mains at 15C today, you should get ~ 17 LPM at 40C, if you are achieving these temperatures and flow rates then there is nothing wrong with the boiler.

The reason I suggested for turning off the water supply at the combi is in case some mixing valve some where is passing cold water which may come out the hot taps with the water isolated at the combi.

50M of 1/2 ins ID piping will hold 11 pints of water & 22M of 3/4 ins will hold the same.


.

 

[ShaunCorbs]

You sure you don’t have pre heat I’m sure the 105 had something?

 

[Mr_GWP]

Nope.. No pre heat. It was installed in February 2006. I'm quite anal with this type of thing.....no eco button.. Nothing

 

[ShaunCorbs]

Thought I read it somewhere

 

[Mr_GWP]

If your right.. I will pay for a night on the razz 😉👍

 

[Mr_GWP]

Ok I have carried out the settings as above..not sure if its pre heating or not. I found out the Baxi manual from when it was installed and there is no mention about a pre heat system 😮
We pay £21 a month insurance on this thing and have done since it was installed 15 years ago. The 2 Baxi engineers who visited over the past 12 months have both said that the boiler is operating with its parameters. .My wife and I both know thats not true....it takes far too long for warm water to get to either the kitchen or the main bathroom.
If we did go for a replacement have you guys any recommendations please ?

 

[ShaunCorbs]

Has much gone wrong with it / replaced parts ?

 

[John.g]

Ok I have carried out the settings as above..not sure if its pre heating or not. I found out the Baxi manual from when it was installed and there is no mention about a pre heat system 😮
We pay £21 a month insurance on this thing and have done since it was installed 15 years ago. The 2 Baxi engineers who visited over the past 12 months have both said that the boiler is operating with its parameters. .My wife and I both know thats not true....it takes far too long for warm water to get to either the kitchen or the main bathroom.
If we did go for a replacement have you guys any recommendations please ?

This is a bit vague about the pre-heat, you said that it performed perfectly up to 18 months ago so letting the pre-heat aside for now you might just consider measuring the flowrate & temperature after the pipe work has heated up after a few minutes, it will be very easy to see then if the boiler is at least giving its rated thermal output, you can then present this to Baxi if its not.

 

[Mr_GWP]

Has much gone wrong with it / replaced parts ?

No not really.. Its had a new expansion vessel and the plate has been changed... Oh and the diaphragm somewhere in it. Its been a brilliant boiler.. Can't fault it up until last year.

 

[ShaunCorbs]

Tbh I would be wanting a new boiler from the cover provider as you’ve paid over 3.5k if it’s always been £21

 

[Mr_GWP]

This is a bit vague about the pre-heat, you said that it performed perfectly up to 18 months ago so letting the pre-heat aside for now you might just consider measuring the flowrate & temperature after the pipe work has heated up after a few minutes, it will be very easy to see then if the boiler is at least giving its rated thermal output, you can then present this to Baxi if its not.

View attachment 62720

The hot water came through quicker than it does now. In the morning you have to run it for ages before any hot water comes through. You turn the tap on and it's cold then there is a sudden pressure increase and then the water will start flow quicker and it very very gradually gets warmer.
Also my wife reminded me that sometimes when taking a shower it drops off cold then warms up again and drops cold and warms up and is ok.

 

[Chuck]

Have one person by the boiler when another turns on the kitchen tap and yells 'on'. Time how long it takes for the boiler to fire up and for the outlet pipe to get hot. Measure how many litre / min your kitchen tap delivers by, e.g. seen how long it takes to fill a one litre jug. How far, as the pipes run, is the kitchen tap from the boiler?

Post your findings here.

 

[John.g]

My mains temp is 20C just now so a 30kw combi should give almost 22 LPM (21.5) at 40C if set to 40C or if set to max (65C) should give almost 10 LPM (9.6) at 65C which will again result in almost 22 LPM at 40C when mixed with 12 lpm of cold mains at 20C.

 

[cjg]

pin hole in dhw diapham, slow to fire boiler hence water runs longer be for boiler fires ????

 

[John.g]

A diaphragm was changed on it. Presume boiler should fire up in say 5 secs? from opening hot water tap, should be easy to check this out.