keston Celcius 25

[kimandrews]

I have a 2002 Keston Celcius boiler to heat underfloor. Plus it heats a tank of water.
In the summer when underflor is off, but hot water is drawn the boiler works for a while but then goes into overheat lock out. When it cools down it restarts and so the cycle continues.

The pressure has been dropping slightly over time. By that I mean a very slight drop on the pressure gague every fortnight and I have been repressurising but cannot find any obvious leak at all in the boiler room area. It has occured to me that there may be a leak in the underfloor but cannot see any signs of one. Given that the underfloor has not be on all summer I think that its is unlikely to be the problem. Any ideas on this?

I have noted that the overheat lockout occurs with or without any drop in pressure so the drop in pressure cannot be the only cause of the problem.

Now that the weather is colder, the boiler is running both the underfloor and the water. The problem continues. I have enough heat, and enough water but the over heat lockout continues daily which cannot be right.

Two heating engineers have looked at it but cannot seem to address the problem. I have cinsidered swapping out the boiler for a new one but am loath to spend the money if the problem is not the boiler.

Any suggestions?

Thanks, Kim

 

[croydoncorgi]

Exactly which lockout do you get? There are several type ('blocking codes' which stop it temporarily) and real lockouts which need a reset to get the boiler going again. I assume it's blocking codes you get.

What temperature is the boiler set to?

 

[ajrobb]

I have two of these ... and both have had cracked heat exchangers causing loss of pressure and condensation on the circuit boards. I've lost count of the number of circuit boards, but I think I've only has 2 new heat exchangers.

 

[XKESTONMAN]

put a container under neath the condensate pipe,whith heating off, over night, see if u get 1/2 litre or more of water in the container,if so the heat ex is pinn holed.
overheating it could be one of the pump speed relay modules in the board.
or the underfloor manifold is sticking. its rare for the temp thermister to fail,but they should be about12ohm at room temp

 

[Agile]

I think that you meant to say 12,000 ohms at room temperature.

I had to go to a big Keston where BG had not thought of the heat exchanger leaking into the condensate drain.

Tony

 

[XKESTONMAN]

yes mate 12000 ohms,yes alot miss leak into condensate,i suppose its
swings arounabouts, it took me a dayto fit two rads a bg guy may do that in an hour, one guy good at one thing another guy good at another.