Glow worm BETACOM 30c Combi Boiler pressure bouncing issues

[davidbrown303]

Hi all,

Having a strange issue occurring with my brand new BETACOM 30c combi-boiler, I will try to explain it as best as I can for you all.

The CH system I have topped up to 1.5 bar via the filling loop, when i turn on my central heating the pressure gauge shoots down to about 1 bar and stays just above that mark until the system and radiators have heated up then it usually reads around or just over the 1.5 bar mark again or perhaps a little higher due to the increase in the temperature of the water in the system.

Upon the pump switching off the pressure gauge needle shoots over (bounces) momentarily to around 2 bar or just over and then drops down to the 1.5 bar mark when it has cooled down.


The other day I had flushed my system and refilled via the filling loop back to just above 1 bar (perhaps 1.2 bar, I realise perhaps a tad on the low side), when the system fired up the needle dropped well below the 0.5 bar pressure and immediately shut the pump off (low pressure) but no fault lights, this allowed the pressure gauge to return back to around 1.2 bar and kicked the pump back into life again, the pump started and the pressure gauge needle dropped to below 0.5 once again and shut the pump off...This proceedure yo-yo'd on and off for a very long time until I switched the boiler off at the power.

Is this normal? I realise that perhaps the pressure was a bit on the low side (ie) 1.2 bar instead of the recommended 1.5 bar from the manual but I have never noticed previous combi boilers I have owned having this much movement in the pressure gauge when in service?

My worry is that rather than shutting the pump off altogether and bring up a fault light (low pressure), the pump will cut in and out constantly bouncing in between low and normal pressure thus burning the pump out on my new boiler?

Any ideas what is going wrong here guys, as I stated earlier the combi boiler is brand new, all the rads have been bled of trapped air but maybe require a little balancing if anything but nothing major.

Thank you in advance and I hope this made sense to everyone

 

[davidbrown303]

Just thought it might be worth mentioning that when the system is topped up to the recommended 1.5 bar pressure the system still has the 0.5 bar bounce either way when the pump cuts in and out but the system runs fine and all rads get nice and hot

 

[GrahamM]

Boiler off and system cool, bleed all rads. Topp up 1.5 bar. Boiler on. As long as pressure is not dropping/rissing dramaticly, leave it alone.
Pressure will fluctuate slightly in operation, but if everything working ok I think you are looking too much into it.

 

[davidbrown303]

Thanks for the reply GrahamM, and I guess under normal operation set up at the manual stated 1.5 bar the system would run flawlessly but what about over time when my pressure decreases, perhaps I am out for the day or in bed asleep and my pump is yo-yo'ing on and off until someone spots the fault and either tops up the pressure or switches the heating off...This has to damage the pump unit surely...This can't be right...Can it?

What does anyone else think on this matter? And why doesn't it just cut the pump out permenantly and bring up a low pressure fault light?

 

[jtsplumbing]

If its a brand new boiler , has been fitted as it should, then why mess with it just call out Glow-Worm !!

 

[davidbrown303]

I thought perhaps I could get some educated help and advise on here first. I've used Glow worms customer service help once before some years back, it was an experience! to say the least

 

[jtsplumbing]

Glow_Worm Tec a lot better now since Vaillant took them over:crazy:

 

[GrahamM]

Again, you are thinking too much here.
If pressure falls to 0.3 bar the low water pressure switch will activate and lock out the boiler until you top up pressure and reset.

 

[davidbrown303]

Again, you are thinking too much here.
If pressure falls to 0.3 bar the low water pressure switch will activate and lock out the boiler until you top up pressure and reset.

This exactly my point GrahamM, when my pressure falls below 0.3 bar it is not locking out my boiler, this maybe because it is only below 0.3 bar for a split second because of the fluctuations I am speaking about and because of this it is constantly stopping and starting the pump and/or closing and opening the pressure switch as the pressure yo-yo's between the 0.3 and the 1 bar.

This will carry on repeating this motion until (a) I turn off the central heating or (b) I increase the pressure via the filling loop so that the pressure drop isn't so low as to go below 0.3 bar.

 

[GrahamM]

Maybe you just have a faulty pressure gauge. This is not a functional component and is just a visual means of reading pressure.
The Low Pressure switch is unlikely to be faulty, but if you really want to keep poking and prodding, just drain all water from system and try fire up boiler. The low pressure switch should lock out.
If you really want this sorted, get out an engineer to look at it, but you pay end up only paying for the replacement of a slightly dodgy pressure gauge.
I would be inclined to leave alone and stop watching your boiler if hot water and heating functioning normally.