How to take fan out of a Ravenheat HE85 T combi boiler

[psarinuk]

Hi all

I have a hot water issue where the boiler is turing OFF after 30 seconds for 10-15 seconds even when the flow rate is constant. I've been advised to check and clean/ replace the secondary heat exchanger..

I've managed to take off the panels, take the electrical connectors of the fan to get to the heat exchaner but can't take the fan off...

It seems its stuck on to the exchanger whereas the manual says carefully "withdraw" the fan from exchanger and then from appliance... I can't even move the damn thing, there seems to be some yellow paint/ rust like layer formed outside at the point where the tube frame of fan goes into the exchanger...

Any idea how to remove this please? Its a RAVENHEAT HE85 T combi boiler... I was thinking of ringing them up but they only answer technical answers to CORGI registered professionals..

Thanks in advance.....

 

[Vinno]

Because you dealing with the combustion chamber the clever people will not answer but your problem may be the plate heat exchanger as your problem sounds similar to mine. Post a detailed description of your prob and the answers will flood in.

 

[Gasman62]

......but they only answer technical answers to CORGI registered professionals..

Thanks in advance.....

There's your answer then????



Better to be safe than sorry............

 

[ChrisR]

You're going into the wrong part of the boiler.
That's the bolt-on afterthought type second heat exchanger, not the one with the hot water in.
You want item 2 on page 4 of the manual.

Maybe it would be best of you got someone who knows one end of a boiler from the other?

 

[bengasman]

Also, cleaning/replacing plate hex is analogue to replacing the tire when your drive is full of nails.
Get it powerflushed and the problem disappears and stays gone.
A lot cheaper in the long run than a new hex every year

 

[psarinuk]

Ok, thanks for your reply..

Am I right to assume that the boiler won't need to be opened for powerflush?

Also how much should I expect to pay for powerflush? Any recommended people to get it done from?

Thanks..

 

[Slugbabydotcom]

Why are you digging in towards the main HE when the secondary HE is what you are trying to eliminate?
Its probably down to the CH thermistor if it has a wet pocket type.

Ravenheat have a list of approved installers who can sort this mess out for you.

0113 2527007

 

[psarinuk]

"

cleaning/replacing plate hex

" - is this primary H/E or secondary? So many terms for an exchanger...

Are you saying that powerflush would only remove the sludge from primary and not secondary H/E (which seems to be dirty at the moment)?

You're going into the wrong part of the boiler.
That's the bolt-on afterthought type second heat exchanger, not the one with the hot water in.
You want item 2 on page 4 of the manual.

Maybe it would be best of you got someone who knows one end of a boiler from the other

Chris
Thanks but I know this. If you could check manual again, it would tell you that removing fan and condensing heat exchanger as pre-requisite for removing DHW hot water exchaner.

Could you give any pointers on how to remove the fan now?

 

[psarinuk]

No reply then??

Yesterday I tried to clean the system one rad at a time by leaving the mains feed into boiler ON and draining through one groundstairs radiator... Left the CH thermostat in MIN mode so the pump would run but would not waste much gas..

Water coming out was quite pure. However, I was disappointed as in the end when I bled the system, some radiators were giving out light red water from bleeding valves, so I guess my efforts really haven't done much as the cleaning acid is still inside...

I am thinking of taking off one rad at a time and jet washing it in the garden on a nice sunny day as well as as draining all the water through pipes all over again.

I've bought magnaclean which when arrives I will install.. I also plan to buy those magnets that you put on mains supply and boiler CH return that help reduce limescale.
Bought the system protection yesterday but would only install it once my boiler gets serviced and the DHW starts running without cutting out... which is my nemesis at the moment..

Any thoughts anyone?

 

[Slugbabydotcom]

Why are you digging in towards the main HE when the secondary HE is what you are trying to eliminate?
Its probably down to the CH thermistor if it has a wet pocket type.

Have you bought a new CH thermistor yet ?

"
Quote:
cleaning/replacing plate hex
" - is this primary H/E or secondary? So many terms for an exchanger...

Primary or main HE is the one with the 'fire' underneath it
Secondary or plate HE is the overgrown sardine tin below the combustion chamber.

Bought the system protection yesterday but would only install it once my boiler gets serviced and the DHW starts running without cutting out... which is my nemesis at the moment..

Better to tackle this the other way round and fit the magnaclean first so you dont knack up the new thermistor.

Yes I know the problem is DHW cutting out but the problem is nearly always down to the the CH thermistor and this has gone wrong because your system wasn't clean.

 

[psarinuk]

Thanks for your reply slugbabydotcom..

I can really progress from here...

No, I've not bought the CH thermistor yet. Could I buy it from B & Q or somwhere you would recommend? Is there only 1 thermistor for DHW and CH? Any other names for thermistor?

Also, my magnaclean has not arrived yet, but I will install that first..

Also to clean the system, I am going to follow this post:
//www.diynot.com/forums/viewtopic.php?t=38902&start=0&postdays=0&postorder=asc&highlight=

Seems quite easy as there is a drain valve fitted already under my boiler. There is also a drain valve fitted at downstairs radiator. Which one should I use for draining dirty water?

Thanks once again...

 

[Slugbabydotcom]

2 thermistors one for DHW and one for CH part number 0007TER05005/0 available from your local gas parts suppliers or internet boiler spares sites.
They don't like us advertising on here but you could look up some european spares or perhaps a firm that likes to keep the heat on.

If you are DIYing the thermistor replacement follow the instructions in the manual and dont be tempted to do it unless the boiler is stone cold. You may need some PTFE tape for the threads and a 13mm ring or box spanner would be handy.

Re:- Which drain valve ... Well I'll leave that to your common sense.

 

[psarinuk]

Thanks for the part numbers mate. It helps greatly...

Could you check page 3 on this link and advise if the 2 thermistors I am getting are parts 17 (DHW Sensor) and 34 (CH sensor) on this parts diagram?
http://www.ravenheat.co.uk/pdf/CSI85/CS185ScreenV3.1pdf.pdf

I read on the forum that you advise "dry pocket replacement". Is this something that needs to be specified when ordering or does your part number ensure this?

I could locate the DHW thermistor but could not find CH thermistor using this diagram. Any clue how it looks?

Also I did mains flushing through all the drained rads and got all the sludge (about 8 bucket fulls). I've got the inhibitor as well now but would only add it after installing magnaclean which is arriving tomorrow..

Cheers...

 

[Slugbabydotcom]

I read on the forum that you advise "dry pocket replacement". Is this something that needs to be specified when ordering or does your part number ensure this?

I find that the newer wet pocket sensors which have a blue ring around the base seem to be better than the earlier ones without. A good job really because I can never get hold of the "dry pocket" clip on type. I am told that you have to ask specially for them. In the meantime the wet pocket type tend to be a stock item so thats what gets fitted

I could locate the DHW thermistor but could not find CH thermistor using this diagram. Any clue how it looks?

Not hard at all ! Look again on the picture for numbers 34 and 17 you will kick yourself when you see it!

 

[psarinuk]

Hi again

The DHW thermistor on my boiler is like a wet screw-on type, however the CH thermistor is a clip on type.

Should I replace both in this case or just the DHW one? If I should get the CH thermistor replaced as well, could you please pass any instructions whether it should be replaced with a 'wet' one and how?

Also there is some white powder like substance around the clip on type CH thermistor. What is it exactly? I've wiped most of it around the thermistor but should I remove it and clean both contacts properly?

Thanks..