Potterton Heat Max 28

[indy scooby]

Firstly hello to you all.

I have a problem with my boiler it lights as normal when I turn the tap on but then the tempreture races up to 90
Then the flame goes out the temperature slowly drops and then the flame relights this process continues until you turn off the tap. My plumber called potterton they told him to test the DHW sensor which he metre set on 20k OHMS he got a reading of 1.9 they said this was fine and that it must be a blocked heat exchanger. However, I have a very strong flow and it doesn't seem to do this when the central heating is on.
So this leaves me two questions
1) how have I got such a strong flow if the heat exchanger is blocked
2) Does it use the CH heat exchnager when thats on.

Hope you can help

Many Thanks

Phil

 

[M.Joshi]

You may have a strong flow but if the differential between the flow and return is high, this may indicate a blockage.

Edit: I just re-read your post. If it doesn't happen when the heating is on, could be the (secondary) plate exchanger is scaled up.

 

[jtsplumbing]

As Joshi, sounds like plate EX, could have dirty system, causeing plates to clog up !

 

[Billy Bob Bob]

it is​ the plate heat exchanger and points to a dirty heating system

 

[indy scooby]

thanks for you replys guys.
i seem to have only one exchanger shown in the parts section but it is listed as a plate heat exchanger so im guessing that it is this one.however if i only have one does it still mean that it is a dirty heating system as i had this fully cleaned and a magnet fitted when the boiler was fitted 19mths ago or could it be hard water?
many thanks
phil

 

[JAP&H]

Hi Indy.

There are two heat exchangers on the potterton heat max range.

Main and plate to plate.

As others have suggested, restriction in flow through plate to plate would cause rapid temperature rise and flame loss during hot water draw off.

Main heat exchanger ok as you have stated the boiler works fine in CH mode.

Options are to remove and clean existing p to p hex (not always successful) or renew it.

Whats the warranty period? I would have thought a 19 month old Potterton would still be 'in'.

 

[fixter1]

you get 2 years with the heatmax

 

[indy scooby]

thanks for the heads up guys..
i just called them and it is in warranty,,,,they are sending someone tomorrow..
happy days...:hurray:

 

[JAP&H]

thanks for the heads up guys..
i just called them and it is in warranty,,,,they are sending someone tomorrow..
happy days...:hurray:

Hi Indy

Any possibility you could let us all know the results of the Potterton blokes visit tomorrow?

Cheers.

 

[indy scooby]

will do for sure..

 

[indy scooby]

ok the engineer came and it was exactly as described.. heat exchanger blocked on the CH side...
he only had a 12 plate insted of a 9.. result... thanks once again....

 

[galaxy_plumbing]

Happy chap now 😉