Glow worm compact 100e combi - Hot water / boiler trip probs

[beefster]

My Glow worm compact 100e keeps intermittantly tripping when the hot water is in use. Sometimes it is twice / three times a night other times we can go for a week without any problem??

No warnings / temp fluctuations.

I have had a problem a couple of years ago with the heat exchanger being blocked... this was taken out and flushed out. Could it be this again?? Previously we had temp fluctuations when this was the problem. that isnt the case at present ??

Anyhelp welcomed

 

[beefster]

Anyone any pointers.... any help welcomed

 

[Gasguru]

Do you mean Compact 100e?

What's tripping. You mean the lockout led is coming on?

 

[beefster]

Yes, sorry...... Compact 100e

Red trip light comes on, boiler locks out. Reset and away it goes rarely tripping again very quickly??
Usually more of a problem when using the shower..... which is a total pain as you will recognise.

 

[ChrisR]

Not really obvious. Not to me that is!
Is it the same problem you had before?
I'd be clipping temp probes around its insides to see what's occuring.

 

[mickyg]

most likely a flow problem, heat exchanger etc.... o'heat trips at 87 and the boiler ntc's won't kick out til 82, so obviously it doesnt take a massive restriction to hit the o'heat temp. the max temp can be altered using the pots on the pcb. but this should only be done by someone who knows what they are doing. in any case, this won't fix the problem, just cover it up.

 

[Gasguru]

You need to determine whether it is locking out due to over temperature or failure to ignite. The burner pressures for hotwater and heating can drift upwards on these, the boiler could just be burning to much gas. I've also had a few with faulty thermisters/overheat stats.

Normally a clogged secondary heat exchanger will not cause an overheat on these, the burner just drops straight to the minimum rate.

Ignition lockout could just be a missing cap on the sample point (on top of boiler RH side) or a missing flue restrictor. Sometimes they work for years with no problem then decide to play up.

Otherwise there's plenty of other reasons but all corgi teritory though.

 

[beefster]

Checked the temps on the hot water o/p and it is fluctuating. The shower unit was compensating so it was not easily felt.

Not an ignition prob as boiler is alight and runs until it cuts out after 10 mins or so in the shower.

Leads me to think its the secondary heat exchanger again. I took it out a couple of years ago and a plumber mate gave it a soak in a cleaning / flushing agent and it was gleaming when he gave it back... worked fine for a couple of years.... now playing up again.

Going to invest in a new one and get the old one flushed out again.. a ready spare.

Have read today that heated towel rails in the heating system can cause probs with contamination and lead to blockages of heat exchangers. Apparently I should add double the inhibitor into the system?? Can only assume thats down to what they are made of??

Not that i am going to play with the gas side but was corgi registered previously. Now work on air conditioning and controls.

 

[Gasguru]

Going to invest in a new one and get the old one flushed out again.. a ready spare.

Have read today that heated towel rails in the heating system can cause probs with contamination and lead to blockages of heat exchangers.

Seem to remember the secondary heat exchanger on these is extortionate price so clean the old one again.

The main problem with heated towell rails is the appaling quality. Bang a brand new rail on the ground and you often get two molehills of scale. They need thorougly rinsing through and some serious stick from the rubber mallet before fitting. Then p**s about trying the get the rad tails to seal with only a couple thread turns in the towel rad fitting.