Rusty heat exchanger?!?

[sabred]

Hi...

I recently removed the heat exchanger from our somewhat aged Glow Worm Fuel Saver 40B MK2 central heating boiler, after getting banging and whooshing noises from the boiler itself. I poured in a bottle of neat descaler and left for fifteen minutes, and watched much bubbling and gurgling for that period of time coming from both feed/return pipes of the exchanger - with hose pipe spraying the area incase of weak acid eruption... Quite a bit of 'rubbish' was eventually hosed from the exchanger, and the jetwash dislodged quite a bit more. But the flow rate through the exchanger was much reduced still, about seventy percent I'd guess, considering the power of the jet washer.

I re-connected the exchanger and filled and bled the system and started up, but the boiler cut out after much similar noises from its wareabouts!!! I'm now considering removing the heat exchanger again and using using Spirit of Salts from the plumbers merchants (Hydrochloric Acid) to hopefully better clear the exchanger pipework, but am aware of the danger of using such powerful acids without proper safety setups...

Can anyone suggest some safe ways of using the acid salts, or techniques or dilutions prior to commencing a thorough cleaning of the heat exchanger!?!

I've also recently completely drained the system several times, and at last have clean water draining very fast from the six drain points on the ground floor.

Any help or tips would be gratefully appreciated...

Tony D

 

[darren17]

get yourself some fernox ds40 add to system and run for no more than 4 hours
then flush system ,refill and pressurise
the ds40 is an acid and it comes with nutraliser sachets but this very strong and will clear all of your system
don't forget to add inhibitor after flushing the systemjavascript:emoticon('')

 

[sabred]

Hi Darren...

Thanks for speedy reply...

I think the heat exchanger is so blocked that the boiler flow rate thingy cuts the boiler out after a minute or so... I actually have the DS40 kit standing idle in the garage ready to use, but without the boiler working can't use it...! Damn...!

When I had the heat exchanger off/out last, even the powerful jet washer gun when fully rammed (gently though) and fired at its highest pressure setting through each end could only manage a small fountain stream of water at opposite end...

I'm believing the boiler is cutting out due to overheating because of poor flow rate, as when it was working previously, it only liked to do so at low thermostate settings...

 

[darren17]

well you can take out the he and leave it soaking for a few hrs in the ds40 but you will have to aggitate the solution by movement
this is a cheap fix compared to having to buy a new he
my e-mail is in my profilejavascript:emoticon('')

 

[sabred]

Yeah I was thinking along those lines, about using the DS40 as you say, as a safer alternative. But I'll have to go buy more DS40 - not cheap - to do the system if this works?!? Better than a new boiler I guess!!!

If anyone has any thoughts on the Spirit of Salts usage (or any more exacting cleaning of heat exchanger whence dis-connected ideas) I'd be most welcoming...