Combi boiler delivers hot water then luke warm

[BGLucky]

No problem, I think the best thing is for you to call customer relations and get them to pass to manager ASAP , it isn't necessarily a complaint against the engineer but there are obviously some concerns that need to be addressed.
Yes I work for BG in London area. I hope this gets sorted for you.

 

[AGAS]

OP ,when the temperature drops on hot water does the burner extinguish on boiler or just modulate up and down . i think the turbomax suffered from broken temp spindles on front of boiler iirc ( which turbomax thou ) . wondered if he actually cleaned the plate properly ( both sides )

 

[Agile]

We still don't know where the OP lives!

Lovely to see Lucky being helpful on here. Its quite rare to see any BG people on here offering to help when things are not going right.

But the technical details being given are sadly lacking.

With heating off, if you run hot water for 10 min then do any of the rads heat up? That would indicate a faulty diverter valve which is a common fault on some models.

Cleaning the plate HE needs to be done by someone who understands what chemicals to use. It needs HCl on the incoming water side to remove lime scale.

There may be dirt in the pump impellor, or in other parts of the boiler.

These really are simple boilers! It should not take long to find out what is wrong.

OP, the temperature shown on the display is the internal circulating water and not exactly what the hot water out temperature is.

Does the hot water temp control knob make any difference to the hot water temperature?

How can anyone even think that microbore piping can have any effect on hot water? Particularly for an engineer to actually say that!

Tony

 

[spiritusuk]

I will be visiting my mum later today so will report back on the questions raised.

The reason I haven't given my location is I prefer to keep this relatively anonymous. The BG engineer is arranging for a home visit with a senior engineer to discuss the problem in more detail. It would be good if I can have some questions to tackle them with as there seems to be a consensus that piping will have no affect on hot water. Could the engineer be making the point that with the piping being too narrow then it is more prone to sludge and blockages which eventually works it's way back into the boiler causing problems with hot water ?

 

[DP]

It needs HCl on the incoming water side to remove lime scale.

I would not like to use HCl on

I will be visiting my mum later today so will report back on the questions raised.

The reason I haven't given my location is I prefer to keep this relatively anonymous. The BG engineer is arranging for a home visit with a senior engineer to discuss the problem in more detail. It would be good if I can have some questions to tackle them with as there seems to be a consensus that piping will have no affect on hot water. Could the engineer be making the point that with the piping being too narrow then it is more prone to sludge and blockages which eventually works it's way back into the boiler causing problems with hot water ?

A pipe carrying any liquid or gas must be adequately sized. There is no guesswork involved.
A radiator will need X number of gallons of water minute to radiate required heat. If pipe bore is too big, radiated heat fine, if bore undersize, then insufficient water circulation to radiator resulting in poor heat output.

By the way, NO one, other than Superman, can just by looking at the radiator and connected pipe, say the setup is wrong. One needs to take temperature readings at various points to then decide if setup wrong.

 

[Agile]

HCl is very quick and effective at removing lime compounds on the DHW side.

Using it at about 5% solution does not seem to pose much risk.

In fact there seem some engineers who use it for the heating side too. Although I prefer to use citric acid most of the time but sometimes will also use HCl instead.

Tony

 

[spiritusuk]

OP ,when the temperature drops on hot water does the burner extinguish on boiler or just modulate up and down . i think the turbomax suffered from broken temp spindles on front of boiler iirc ( which turbomax thou ) . wondered if he actually cleaned the plate properly ( both sides )

The burner (flame icon ?) remains on even when the running water temperature drops.

We still don't know where the OP lives!

With heating off, if you run hot water for 10 min then do any of the rads heat up? That would indicate a faulty diverter valve which is a common fault on some models.

OP, the temperature shown on the display is the internal circulating water and not exactly what the hot water out temperature is.

Does the hot water temp control knob make any difference to the hot water temperature?
Tony

None of the rads heat up whilst hot water is being run although the engineer did remark that one of the copper pipes under the boiler was hot to the touch when it should not have been. He said he had fixed this and the heat was no longer being wrongly diverted..........this hasn't made any difference to the original problem of the hot water though

Thanks Tony. I keep forgetting the temp on the display is not the actual water temp. When the hot water is running the temp display drops in sync with the actual temp of the running water hence my mistake. Presumably there is some correlation between the two.

The hot water dial DOES make a difference to the temperature of the water. In my recent attempts to get a bath of hot water for my mum I have been moving the dial to almost maximum position believing that the bath would fill quicker with hot water. The engineer advised me that this could have an adverse affect and suggested the dial should be much lower........again this hasn't made any difference to the problem with the hot water temp

 

[picasso]

Be funny if this turns out to be a cold supply running into the hot supply and not s boiler fault at all.

 

[Agile]

OP can you measure the hot water temperature at the boiler outlet pipe?

And then at the tap?

Tony

 

[spiritusuk]

OP can you measure the hot water temperature at the boiler outlet pipe?

And then at the tap?

Tony

At the risk of embarrassing myself, how do I do that ?

 

[oilboffin]

I didn't think you could flush 10mm pipes because the cross sectional area isn't large enough.Bob

 

[Fultonius]

Be funny if this turns out to be a cold supply running into the hot supply and not s boiler fault at all.

I have just had a similar issue with my Vaillant Ecotec 28, 8 months old. Hot water was lukewarm, installers came out, referred to Vaillant. Vaillant came out, checked boiler, no issues - boiler is supplying roasting hot water, but the all the house taps were not supplying hot water... only lukewarm.

As Vaillant man was leaving he suggested checking the mixer valves on all the taps. Before he left he showed me the hot water outlet isolation on the boiler, which we turned off and tested the kitchen tap - out poured cold water with the mixer turned full hot!

He left.

I then turned the hot water isolation valve back on and turned the cold water isolation valve for the kitchen mixer tap off. Bingo, the hot water was now roasting hot all round the flat. So, faulty ceramic mixed cartridge in the tap to blame, nothing to do with the boiler. It amazes me that trained, qualified "engineers" are so poor at basic fault finding through a process of elimination. Diving straight for "power flushes" etc.

To test the temp difference, put your hand on the hot water outlet of the boiler, at the boiler (might need to google your model to find which that is) and see how hot it is. The, cpmare that to how hot your water is. If it's significant colder at the tap, you might have the same issue as I did?

How on earth flushing the heating system could affect the tap temp I have no idea, they are not the same system!!

 

[Fultonius]

Thanks Tony. I keep forgetting the temp on the display is not the actual water temp. When the hot water is running the temp display drops in sync with the actual temp of the running water hence my mistake. Presumably there is some correlation between the two.

Hmm, to me that says the boiler really isn't putting out hot enough water, rather than the mixer issue I just commented on.

 

[spiritusuk]

British Gas have arranged a visit with a senior engineer to discuss this issue with us. I would like to be prepared as much as possible for the visit as I have a feeling they will try and sell us a re-pipe and power flush job.

1. Am I correct in saying that the width of the piping around the house is not related in any way to the problems my mum is experiencing in receiving steady hot water when running the hot water tap ?
2. If British Gas were to say to me that the narrow piping has contributed to an accumulation of sludge in the system (including the boiler) then could this be a reason they could give for re-piping ?
3. It isn't just the hot water that is the problem-some of the radiators do not get hot-the 10 mm pipe could be the cause-could low water pressure also be a factor ? I would hate my mum to agree to a repipe and then BG tell her "oh, it must be the water pressure-contact United Utilities"

 

[mcmoby69]

1. the size of your radiator pipes are irrelevant to hot water temperature .
2. incorrect pipe size has nothing to do with sludge occurrence . however, non barrier pipe and frequent ' topping up' do.
3. there are several reasons why some rads may not get hot.

Stuck Trv's , sludge accumulated at rad valves, system needs balancing, weak pump at the boiler etc etc.

I would suggest you get a couple of independent local guys in to diagnose and quote. ask around your friends and family for recommended guys, don't just Google them . British gas are a big company, they have huge overheads and a massive advertising campaign to fund. many people think they are the mutts Nutts, but they are only as good as their worst employee. I gain many customers from British gas after stories like this come my way.

The people asking for your location are trying to help you find a reputable chap close to you. not to drop your ' friendly , nice bg guy' in the doodoo .