GLOWWORM COMBI 100E - FLUCTUATING WATER TEMPERATURE

[Gasguru]

I'm not sure what Y strainer you are talking about. It appears you may have a filter fitted on the return heating pipe to the boiler (the 22mm right hand pipe).

There is a filter within the boiler. Is is located inside the lower connection on the pump. You have to remove the plastic elbow leading from the rear frame to the pump. Place a large tray under the boiler..if the filter's partially blocked when you remove it ( with a small screwdriver) you may get a few litres of water.

As for the DHW - unless your plumber can measure the burner pressures to further diagnose the fault it does appear the plate heat exchanger may be blocked. You need a Torx screwdriver to remove it. I think the 4 seals are also non standard so get these beforehand. If it's anything like the 80e model the plate's a complete bast**d to get out. The expansion vessel required serious levering to make some clearance.

 

[kilrail]

GasGuru you are absolutely right , it is a filter on the 22mm right hand pipe, I got carried away with the previous person's description as he seemed to know what he was talking about, maybe he was having a laugh.
The engineer made no mention of doing anything other than a power flush which he said would flush out the heat exchanger as well without removing it. I still think it's a bit steep £375 but I suppose the thing to do is to get a couple of quotes.

I know there is crap in the system cause I saw it today when he cleaned the filter we talked about.


Steve

 

[Gasguru]

Yes but did the filter in the lower pump connection get removed and cleaned...it's inside the boiler.

To clean the plate heat exchanger you must connect the powerflusher onto the boiler with a pump adapter. Ie the boiler pump head is removed and the adapter connected onto the pump back casing. The boiler is then run in DHW mode to ensure the diverter allows the correct flow.

 

[bengasman]

The engineer made no mention of doing anything other than a power flush which he said would flush out the heat exchanger as well without removing it. I still think it's a bit steep £375 but I suppose the thing to do is to get a couple of quotes.


Steve

there is a lot of difference in the way people do power flushes. some do it in a couple of hours, some take a long day from beginning to end, or more than a day for a large house

 

[Gasguru]

For £375 I want him there all day working his b*****ks off. There's too many out there charging a fortune for doing nothing.

Also note on the compact the pressure switch will require temporary bridging out. There were also problems with the right hand hydroblocks cracking so great care is needed removing the pump.

If the filter in the boiler is blocked the rads may appear full of sludge, personally I very rarely come across sludged radiators.

 

[Agile]

Hi Tony

This one is installed on a vertical 22mm pipe at 45 deg pointing down. But I suspect the filter should have been checked regularly. Strangely, the engineer told me today that it not a normal part of boiler service and all they usually do is give it a "bit of a clean"
Do you think the power flush will sort it?

Regards Steve

If the filter nut is "pointing downwards" then thats correct as dirt falls out when the nut is removed.

However most people will not fit it this way because the arrow on the outside the points downwards in the opposite direction to the flow.

Tony

 

[ChrisR]

I wouldn't have the powerflush done in your case. No evidence you really need it.
Check the gauze tubes inside the filter. If there are two, the fine one is really too fine and blocks easily.
You could remove it altogether and fit a Magnaclean or Boiler Buddy, which are magnetic filters which don't impede flow

 

[Agile]

If you fit a magnetic filter then either keep the gauze filter or make sure you fit a gauze filter washer in the outlet of the housing as they only trap magnetic particles and not lime compounds!

Tony

 

[kilrail]

OK here's what is happening now. I don't feel confident enough to remove the filter at the rear of the pump (and would it not need to be isolated to stop flow). The Engineer, on being informed that rads are best ever, hot all over, decided power flush not necessary.
He asked me to do a test as hot water any any temperature setting is still going warm cold and gas is cutting out as before.

I put the system on water only, as directed, and let it cool down then turned on hot water tap full. He said if the heating flow pipe on the left became hot then the diverter valve was dodgy and he would change it. Lo and behold that is exactly what happened.

I don't think the strainer is an issue as I took it out and looked at it myself, it is fitted wrong way up as Tony suggested but there is a drain plug at the bottom of the U section where the filter plug is fitted so you could open that and hopefully the Cr*p would fall out.

The thing I'm not sure about is whether a dodgy diverter valve could be responsible for the gas powering off as I'm not too confident with the Engineer. He said he is glad he solved my heating problem, but it was me who pointed out the filter and asked him to clean it out just to see if it made a difference!.

 

[kilrail]

Apologies, I have just read GasGuru's comments on other post and I will ask my Engineer (although should he not have suggested this) to check the filter and remove the plate heat exchanger and clean it out.

I am learning a lot from this forum and I also downloaded the manual but some of it is a bit heavy for an amateur.

I am tempted to contact the Glowworm people and let them service / repair etc as it's probably unfair to expect an engineer to be an expert on every type of boiler.

I will definitely post when the problem is solved.

Steve

 

[kilrail]

I have just something from one of your previous posts and you referred to a waterlogged switch. At the back of the pump above and to the right hand side there is a black plastic assembly with a small knurled knob on top which seems to rotate freely. There is evidence of water , scale all around the top and coming down the side. Is this normal and it is some sort of relief valve or is it part of a problem? No sign of water now just evidence that there has been some.

Steve

 

[ChrisR]

It's the automatic air vent . They often weep a bit. The cap needs to be left loose.
The head can be changed.

GW would only want to replace the heat exchanger not clean it. Some of them are a bit expensive, check!
Cleaning them isn't a specialist thing to do, for a boiler man, though some won't want to do it.
I've just checked the manual, I remember doing one of these, nothing unusual about it really.

 

[kilrail]

Thanks Chris, one worry gone now I know what it is. I don't suppose anyone has any comment on whether diverter replacement would solve the hot water issue and the gas on for 20 secs off for 10 secs problem, or should I get the Engineer to clean out the plate heat exchanger and the filter that GasGuru mentioned and see what happens

As he suggested diverter valve he might think I am taking the mick to make other suggestions - he doesn't know I am picking the brains of you experts on here.

Further comments , suggestions will be gratefully recieved.

Steve

 

[kilrail]

Just to let you guys know, who all gave good (and some not so good) advice and comments, I gave up on my Corgi Engineer and called in British Gas. I met an extremely competent engineer who knew his stuff and wasn't afraid to discuss with me. Based on comments here I was fairly certain it was a blocked plate heat exchanger and indeed that is exactly what it was (GasGuru spot on). He also decided to change the diverter valve when he had the boiler to bits (just in case ).

Incidentally, for anyone who is interested the Mira Excel shower (which first highlighted the problem) is also performing well and I have solved the issue of why I was getting hot water on the blue instead of say No. 5 on the dial. It was simply a matter of turning the switch on the back of the thermostatic cartridge slightly away from high and not right on it. When I moved it right to low, the water was only lukewarm on No. 9. It looks like trial and error, moving the switch until you achieve the setting you are happy with, although I'm sure some of you clever chaps would solve it with meters etc.

Anyway, thanks for all the help and comments - hopefully I won't need to post again.

 

[clarkeysparkie]

Hi there.
I have a gloworm combi boiler fitted.
The heating works fine. But the hot water seams to go from hot to cold while the tap is left open.
I had British gas come around, they told me it need the heat exchanger cleaning and a power flush.
So i had this done. But guess what. It didn't fix the problem.
Any ideas of what it could be?.