Potterton Netaheat 10/16 rads gets very hot

[mikej100]

I have a problem with the boiler in our house it's a Potterton Netaheat 10/16 probably original which would make it about 28 yrs old and has behaved itself so far but in the past few days the radiators have starting to heat up very quickly in about 20 mins all the rads are so hot you can hardly touch them i suspect that the thermostat on the front of the boiler might be on it's way out but does this control the temp of the rads or the hot water any other ideas on what it might be would be much appricated...one other thought ,we live a very hard water area could this be contributing in any way.
Thanks
Mike.

 

[75pete]

Have you got a room stat?
Does the boiler cut-out when you turn down the boiler stat?

 

[mikej100]

yes there is a room stat downstairs in the dining room it appears to be working correctly but i turned down the thermostat on the front of the boiler to below minimum this morning before the heating came on and the rads ran at their normal temperature ,so i'm leaning more towards it being the stat on it's last legs.
Mike.

 

[Timmyturtle]

Sounds like the stat.
They do go with age (like the rest of us)

 

[mikej100]

Which stat do you think it could be he room stat or the one on the boiler because tonight even though i turned the room stat right down the heating kept going i had to turn the boiler stat down to off to make it go off....might just replace both and be done with it.
BTW thanks guys for your help much appriciated
Mike.

 

[petit_pablo]

If the boiler is still firing with the room stat turned down i would check the heating motorised valve isnt stuck open.

 

[mikej100]

Where would i get a stat for the boiler? and how can i tell which room stat i need the existing one is a horrible brown rectangle Honeywell thing.
Mike.

 

[Agile]

The boiler stats do age and lose their calibration and increase the hysteresis. Probably cost about £20.

Room stat should click and turn off boiler ? ?

Room stats start at about £12 so might as well change it anyway.

As your boiler is well due for replacement, I suggest you get a two wire or combistat which will be suitable for any replacement boiler.

Tony

 

[mikej100]

the existing stat has 3 wires red,blue and yellow so have bought a Honeywell 6360 which if i'm right will do the job but have trierd to order a replacement stat for the boiler but am struggling to find one.

 

[mikej100]

Right...have fitted the new room stat didn't make a bit of difference when i fired the boiler up it began to heat the rads even though the room stat was right down so i guess the 3 way valve is stuck anything i can do to it or is it £75 for a new one?

 

[petit_pablo]

I did suggest this, o well

What type of valve is it? Make etc.

 

[Timmyturtle]

If the boiler stat is turned right down and operating correctly, the rads shouldnt get TOO hot ,wether the heating is on all year or just 10 minutes