Water temp on a compact 100p

[bridgey32]

Could someone tell me if it is possible to reduce the central heating water temp on a glowworm compact 100 p boiler. At the moment my rads are just to hot.

 

[Agile]

It is, but only by modifying the boiler internally by adding a variable resistor in parallel with the temperature sensor.

But that is not supported by the manufacturer!

The boiler was made as a simple design to give a flow temperature of 80°C and relies on the room stat to turn it off when its reached set temperature.

Tony

 

[gasgeezer]

you can by adjusting the potentiometer on the pcb

 

[bridgey32]

Which pot is it i have a p1 and a p2

 

[rcssmb]

Hi
having the exact same problem, did you find out if it was P1 or P2 to adjust?

 

[Agile]

I dont think thats correct advice!

I think the two pots control the maximum CH power and the maximum HW power.

Thats not the same as controling the maximum temperature!

I am saying this from memory without looking at the manual so I might be wrong.

Tony

 

[rcssmb]

Hi
Yes the two potentiometers available without removing the control board cover are for the burner pressure. The adjusting tool has two ends the other end adjusts the potentiometers 'under the cover'.

Guess I can mark their current positions up and make adjustments to see.

Thanks for the reply

 

[Agile]

I am sorry that you dont want to take my advice!

Firstly they will NOT achieve what you seek!

Secondly as you have no understanding of boiler operation or any means to measure the burner pressure its illegal!

Tony

 

[rcssmb]

I know that I can acheive the desired affect because this is simply a replacement board. At instalation the adjustments were made to the original board by the engineer, I just wanted a heads up on which one of two to adjust.

I was aware of the affect of the other potentiometers on the pressure and have no need to adjust these.
Thanks

 

[Agile]

I know that I can acheive the desired affect because this is simply a replacement board.
Thanks

The burner pressure controls the POWER input to the boiler!

You want to control the rad temperature!

You can set a power to give a particular temperature but as the weather changes the heat output required will change.

I do agree that you will be able to improve the situation somewhat but it will not be controling the flow temperature because the designers chose not to make it user adjustable.

As a starting point set the flame height to about a quarter of the maximum.

Tony

 

[rcssmb]

Hi thanks for the advice, If you turn potentiometer P2 clockwise (approx 30 degrees) this adjusts the central heating temperature down to a sensible level. (Note this IS the temperature setting and not the power output which has its own adjustment) As owners will know it is preset at 80 degrees with the safety cut off at about 83. Every week or so you find you have to relight the pilot. At 80 degrees the radiators are imho unsuitable for families with toddlers.

Lucky for us the original installer (retired) knew how to adjust the temperature but not the guy who fitted the replacement board. Happily adjusted now.

 

[Agile]

I hope that you are right!

My advice is usually given without consulting any manuals as I just do not have time on forums (except for paid clients).

All I can say is that virtually all other boilers only have an adjustment of the burner pressure which equates to the power input. Of course burner pressure will also alter the radiator temperature!

Tony

 

[mickyg]

He is right. There is a temperature adjustment, but it is not in any manual and not indicated anywhere. Its a trade secret tony

 

[Agile]

I will have to check that the next time I am unfortunate enough to go to one of those.

Either they are quite reliable or not many fitted as I only see one or two each year.

Tony