Low flow from hot tap

[webbm]

Hi

I have potterton he 28 since yesterday the hot water flow through the boiler is very low and make whistling/hissing sound coming from the boiler.

I turned the boiler off and the flow is still low on the hot tap and still makes a hissing sound. Tried all the hot tap throughout the hose and it same issue.

Cold water flow is is still good and central heating is working fine any ideas what it could be?

 

[ALCPlumbing]

The plate heat exchanger could be scaled up to the point it is restricting the flow of water. Is there a scale reducer on the water main feeding the boiler.
You need to call a boiler engineer who can diagnose this problem properly and clean the heat exchanger out or replace it if need be.

 

[webbm]

no scale reducer but the boiler is just over 2 years old

 

[AlexCarp]

no scale reducer but the boiler is just over 2 years old

Do you have very hard water?

 

[webbm]

Do you have very hard water?

no

 

[McCombi]

I'm not 100% maybe someone could clarify, do these boilers have a filter on the cold mains in like the Baxi 105 etc?

Could be that it's choked up.

 

[webbm]

I'm not 100% maybe someone could clarify, do these boilers have a filter on the cold mains in like the Baxi 105 etc?

Could be that it's choked up.

#

The noise comes from the inlet pipe , just after the switch to isolate the mains water.

 

[Agile]

Depending on the exact model there is a filter and flow regulator on the water inlet.

I suspect that the flow regulator has failed or become blocked.

Regardless of the exact cause that part will need to be carefully dismantled and examined.

It is unlikely to be the plate HE as your water is fairly soft and any scaling of the plate will have been a slow process over many weeks.

Its a tricky job and not something all engineers are very conversant with but is something a DIYer could attempt in theory although I would not advise it unless they worked in avionics or something related.

Tony

 

[webbm]

found this

• webbm
• 20 Jun 2014
• 1

y

DHW Filter (Fig. 79)
13. If the flow of domestic hot water is diminished, it may
be necessary to clean the filter

found the above is worth asking a boiler engineer to check it for me because the one I called out was not sure what the problem was he said it could one of 2 parts and would he need to change both to find out the cause he wanted £320

 

[Agile]

It will either be the restrictor or the filter blocked.

Those kind of prices are stupid and probably covering his lack of experience of these problems. I expect it just needs cleaning at no parts cost.

Should be about £84.

Tony