Vaillant Eco Max 824E - Very slow hot water flow

[JulesJules]

Hi everyone. Hoping that a knowledgeable heating engineer might be able to point me in the right direction with this problem. My 95 year old MIL has the above boiler. Hot water pressure is non existant and tbh I think it has been for a long time. She had the boiler put in when she moved in to the property and it's 15 years old. The cold water pressure is normal. There are three hot water outlets - 2 in bathroom (sink/bath) and one in kitchen. All have the same problem.

The central heating works absolutely fine.

When the hot water is first turned on it comes out as if it's going to be OK but then tails off to its very slow rate. Impossible to wash up with... have to use a kettle. I don't think she has realised how bad it is (age/memory).

A few months ago an engineer came and changed the heat exchanger. That didn't fix anything but the engineer seemed satisfied.... does that mean that the boiler is working fine but there is a problem elsewhere?

Any suggestions appreciated please as it is making life a bit difficult atm.

Any chance it is the Diverter Valve Actuator? Possibly not opening fully for the hot water?

 

[Hason]

Check if you have scale reducer on cold by boiler as I have seen loads cog up,or check cold supply to boiler isn't cogged up. Also cut hot pipe under boiler to see what pressure is like.hope this helps keep us all posted

 

[JulesJules]

Many thanks Hason. She has an insurance policy on it hence the heat exchanger fix. I didn't really think the engineer covered all bases.... as in, it still didn't fix the problem. I wanted to get some professional advice on what the problems might be so I could talk to the next engineer who goes to check it out. (Not easy since it's a long drive away and the appointments are never on time). I will google what a scale reducer looks like. Would the radiators still work fine if the cold supply to the boiler was slow? (They are fine).

"Cut hot pipe under boiler"? Do you mean check the rate of flow in the hot pipe leaving the boiler? Is that an easy job?

 

[JulesJules]

Thanks to Hason for your reply. The problem is fixed. We were extremely lucky to get a heating engineer who specialised in Vaillant and knew what he was doing. He said there were two inline filters which he cleared using acid... the system is now running perfectly again, with the hot water pressure as good as the cold. The engineer who called last year gave up after replacing the HE and said that there was a problem somewhere in the existing pipework... we hadn't wanted to start pulling up floor boards as MIL is heading for her centenary and would have been too much of an upheaval (I don't think first engineer knew what he was doing - the HE replacement was probably not necessary and a 'go-to' with that sort of problem). Just goes to show that the right person can work things out really quick (his visit was little over an hour).

 

[Agile]

A fault like that is a very easy fix but it does require someone with the desire to sort it out.
Unfortunately, some working for those insurance companies are less motivated and take the easy solution.
I always think that a good independent is way better and cheaper across a few years.
Tony

 

[JulesJules]

Agree with you there. Took the engineer's details for any future problems. Trouble is it's the luck of the draw whether you get someone who knows his stuff or someone like the first engineer who didn't have the experience behind him and winged it (he shouldn't have told us that the problem was elsewhere in the original pipework though). Would have thought in those situations that the inexperienced guy would have colleagues to call upon to solve the problem.. There was no mention in the installation/running/comissioning instructions/booklets about the filters either.

 

[Agile]

I suspect the first guy guessed what might be wrong and changed it. Then when it was not solved made up a non boiler reason so he could leave.

Making it easy for himself rather than a lack of experience I think.

When identifying a blockage it involves taking several parts out to check each one at a time.

Tony