Glow Worm Ultracom 30HXi HW Problem

[vinayparmar]

Hi. I have recently noticed an odd problem.
Boiler runs perfectly when CH and/or CH/HW demands.
Problem occurs when ONLY HW demands.
Boiler seems to exceed required set temperature (by 2 Degrees) within 60 sec and turns itself off. It continues to start and stop in the manner indefinealtely. It continues to do so pretty much until CH comes on.
I have range rated it to 18KW still same problem.
It seems when the boiler fires up it fires up on maximum and doed not modulate down quickly enough.

Any ideas?

Regards
Vin

 

[hertsboilers]

When HW is demanded the boiler is firing on full rate. It seems a heat exchange blockage.

 

[vinayparmar]

When HW is demanded the boiler is firing on full rate. It seems a heat exchange blockage.

I should of mentioned in my earlier post.
The boiler is brand new only installed 2 weeks ago.
System is clean with magnaclean in the return pipe work.
I only noticed the problem when the CH has reached correct temperature and ther is HW demand. I noticed the temperature on the boiler rising a lot quicker as the run to the cylinder and back to boiler is massively shorter and the power demand is much smaller.
The boiler does attempt to modulated to a lower flame but its exceeds it limit and cuts out. Only once in a while it continues to stay a light and it does modulate up and down quite a lot. (the water temperature in the pipe work which travels to the cylinder and back is vastly different hence continued modulation of up and down).

My installer has looked at it and said its a Glowworm control issue. It been installed correctly and his not sure what else he can do to help.

My concern is when the weathers warmer and there is little CH demand, will my Hot water be hot enough?

 

[vinayparmar]

quick update,
The temperature set on the boiler was 65 degrees when this problem occurs.
I have just set it on 75 degrees and hey presto it seems to now work on HW only.
Very strange.

I''ll lower it to 65 later and see if i can replicate the fault.

What temperature should the boiler be set to?

regards all

 

[mickyg]

your hot water circuit is either to restrictive or not drawing enough heat.
Have a look in your manual where it mentions D codes. Check your d code 40 and 41 when this is happening. If D40 is rising quickly and 41 is not changing much then the circuit is restrictive, if D41 rises quickly to your set temp and the difference between them is low then the hot water coil is not drawing enough heat.
Im gonna hazard a guess and say the boiler is grossly oversized, unless you live in a mansion

 

[Agile]

Probably a two bed terrace and a small old cylinder.

Who chose that boiler size?

 

[vinayparmar]

Probably a two bed terrace and a small old cylinder.

Who chose that boiler size?

Hi, my home is 5 bed detached. 17 rads + cylinder open vented on a y plan layout. The installed option board is controlling the heating of CH/HW

I have currently set d.0 at 15 ( ok its running at half it's capacity)
But it's running perfectly.

When boiler is running on demand
The temp difference gets to around 17 degrees on CH and CH/HW
The temp difference gets to around 10 degrees on HW

I'm leaving as it is for the time being. Seems to be running comfortably.

If anyone has any ideas how to derate system just for HW would be most helpful.

 

[bell824]

cylinder open vented

here in lies your first problem, vented cylinder coil rating's are generallybetween 3 and 6 kw of heat therefor to much heat power cylinder coil alone,

if anyone has any ideas how to derate system just for HW would be most helpful.

only possible if using full gloworm controls (that includes systempro wiring centre).

bear in mind though this would mean hot water priority so hot water would need to be set to heat about an hour before heating is due.

 

[vinayparmar]

can u confirm please.
if at any time HW is requested it will take priorty to the CH.
so you never have HW & CH combined

Regards

 

[bell824]

NOT WHEN DEMANDED ON THE TAPS NO!!

if you use full glowworm controls they prioritise hot water to get up to temperature first so that it can modulate the boiler for correct heat load once the tank is warm it will revert to heating modulation control for radiators, but if hot water falls below set point it will top up the tank again.

best used on a high efficiency unvernted tank as to minimise heat and reheat times.

not that noticibale on high efficiecy tanks but it would shut off heating untill tank is warm.

 

[vinayparmar]

Thanks again, I was just double checking. I'm probably going to upgrade to that sooner or later.

That resolved I have another issue withe the boiler making helicopter sounds.
I've started another thread for this.
Regards all