Boiler Flow Temperature too High

[Ian400]

Glow-worm Ultimate 50 BF - Boiler supplies a pumped Heating system only.
The Thermostat does not really control the temperature, even when on the minimum settimg the Flow temperature is very high.
I replaced the thermostat but it made no difference.
Would appreciate any advice on the next step
thanks Ian

 

[Boilerman2]

You need to Actually "Measure" the Temperature with an electronic Thermometer and post the results! "Too hot" is a bit vague you would be unable to keep your hand on a pipe at 60'c let alone 90' which is the approximate range of the Thermostat fitted to the Ultimate range of gas boilers so - more info required!

 

[Ian400]

Thanks for your comments boilerman2. I am afraid I do not have an electric thermometer so cannot test it exactly.
However I do remember in the past the Flow pipe was 'Warm' (thermostat on minimum setting) you could leave your hand on it forever, yet now it is very hot, 5 secs and you have to take your hand away.
Sometimes the boiler makes a lot of noise as if a pile of pebbles are being pumped around the system, and I thought of sludge in the heat exchanger preventing the thermostat phial sensing the correct temperature - is this feasible ?
Thanks for your help Ian

 

[Ian400]

Thanks for your comments boilerman2. I am afraid I do not have an electric thermometer so cannot test it exactly.
However I do remember in the past the Flow pipe was 'Warm' (thermostat on minimum setting) you could leave your hand on it forever, yet now it is very hot, 5 secs and you have to take your hand away.
Sometimes the boiler makes a lot of noise as if a pile of pebbles are being pumped around the system, and I thought of sludge in the heat exchanger preventing the thermostat phial sensing the correct temperature - is this feasible ?
Thanks for your help Ian

 

[Servotech]

Try turning the thermostat to off then bring it back using the slightest touch that you can.

Does this alter the temperature at all?

No?

Assuming the new thermostat isn't faulty we need to look somewhere else.

First place is to check is the expansion tank to make sure that you have water in the system

As any other work been done recently, ie replacement pump?

Not really that much else to go wrong with it.

 

[PEDANTICVINDICTIVEMAN]

If the thermostat phial pocket is sludged inside the Heat exchanger, this could cause it to be less sensitive, you need to put a thermometer inside the phial to see what it's reading.

 

[Agile]

The only significant problem which sludge or deposits cause on the thermostat sensor or pocket is a slow response.

This sounds like a boiler fault.

There can be many. Enen incorrect wiring of thermostat.

It really has to be checked back to basics.

Tony