Circulation issues - Glow Worm HX 15

[Colin68]

Here goes! .. me and my very experienced mate are scratching our heads on this one!

set up - convention with 5 x rads and 1 x cylinder (y plan), 22mm flow and return with drop downs to all rads

Boiler is faulting on poor circulation F22 and F25 (glow worm HX 15)

What I've checked :-

1.confirmed Mid position working
2.confirmed pump working (all speeds)
3.confirmed no air lock once filled
4. mid position set to manual open and tried running the boiler and pump
5.run the boiler on heating and hot water independently (still faults)
6.power flushed the circuit
7. pushed water through the heat exchanger in the boiler (rest of circuit isolated)
8. cut the flow and return, attached a hose pipe to the flow (before the zone valve), set valve to manually open with a hose pipe to the return (into the bath), put mains water through the circuit both with the radiators isolated (just flow and return cicruit) and with radiators all on .. water flowing out of the return no problem

Boiler is 5 years old and has some leakage and limescale deposits forming around the flow at the top of the exchanger which has dripped into the bottom of the boiler casing

I am going to discount sensors causing the fault as the return temperature (after the cylinder return) is not getting up and the boiler is shutting down (flow beyond the zone valve both DHW and Heating is confirmed)

I have an 84 year old man with no heating or hot water so it's bugging me a little as you can imagine

The previous idiot has disconnected the immersion heater power (customer was told he would never need it!) and managed to fit the magnaclean on the 'FLOW'

2 x AAV's have been replaced as they were faulty

Any ideas would be welcome????? .. I am wondering is heat exchanger is partially blocked (flow and return temp difference is 40 degrees when running) confirmed via GW diagnostics

 

[Aquazone]

Sounds like an air lock or pump is faulty. Have you checked the pump is actually running and resistances? May be lazy? Magnaclean isolation valves open and chamber clear?

edit: take pump off and check impellers are all intact

 

[Colin68]

sucked the air out of an AAV's as the system filled .. so not an airlock

fitted my new spare van pump still faulting

took the magnaclean off all together

 

[PhoenixServices]

Sounds like the heat exchanger. Especially if the magnaclean was on the flow.
They have such small water ways.

When you power flushed just the heat exchanger was it definetly flowing round , and not faulting.

 

[Colin68]

yeah I put the flusher on the flow and return on the boiler and switched it on but only short bursts as Glow worm advised against it .. I also put a Rothenberger wet pressure testing pump on there with the return on a hose pipe into the sink, some quite big lumps of crap came out but the flow through seemed ok but I am not 100 percent on this

 

[PhoenixServices]

I would put the flusher on for a decent amount of time just on the flow and return, straight off the boiler. And really double check it is flowing round the hoses. If it isn't or seems really slow, then that's your problem. Once you know it's that bang a new one in.

 

[Colin68]

Thanks All for your replies, after much messing about I have removed the boiler from the wall and removed the heat exchanger to be proven right all along this is what I've found





The rubber gasket washer for both flow and return has become twisted, ruptured an partially blocked the flow and return of the aluminum lump! .. The connection between the cast iron and the aluminum using the rubber gasket has caused unrepairable damage to the the exchanger, presume electrolytic action in play here!? .. slightly confused as to what could cause this damage, Glow Worm seem to think that the engineer who fitted the boiler five years ago must have left F5 or similar running round the circuit.

Anyway the old boy will now have a new WB RI fitteed next week. I have never been a fan of Glow Worm as these seem to have all the issues I get calls about .. even some problems with them straight out of the box.

I have decided a letter to Jim Moore (UK MD of Glow Worm) is in order as I am not satisfied with the explanation from Glow Worm technical

If you have any thoughts, please pass them on

 

[Dotty]

moved into the Arms for now. Colin, I want you to get your gsr badge up.

 

[Colin68]

thanks, what do I have to do?

 

[Dotty]

Send a PM (Private Message) with your gsr details to either Gas man - View Profile: gas man - Plumbing Forum | Plumbing Advice | Plumbers Forums | A forum for plumbers advice in the UK or Redsaw - View Profile: REDSAW - Plumbing Forum | Plumbing Advice | Plumbers Forums | A forum for plumbers advice in the UK

 

[IDCHAPPY]

Glow Worm... It's going to be a long cold day in hell before i fit one 😉

 

[Roger Welton]

Flexicoms are nearly as good as isars for work generation I find.

 

[buckley plumb]

its a flexicom fitted a few and had problems with most of them - ignition fault on most glow worm say 50volt to ign unit got about 80v to them ended up being board - called glowworm to them as they suggedted replacing lead ign probe and unit and if that does not work change pcb so was cheaper for customer to call them.fitted a lot of ultracom 2 boilers and had no problems on any o them yet.

 

[buckley plumb]

surprised it was not leaking on the joints