High Temp Thermostat keeps tripping

[Softus]

Have checked again and the 'domestic' side of the HE is a black colour, but not full of scale. Water seems to run through it OK when I've fired a garden hose through it!

How exactly did you remove the scale and sludge from the h/e? For example, a garden hose is woefully inadequate?

The same question applies to the rest of the system - there's little point in replacing the h/e until the rest of the system is clean.

With all of your advice, I think I'm gona have to flush it AGAIN and check what comes out. Might try to get some mains pressure through the rads at the bottom of the house as they seem to not get quite as hot as rads on floors 1 & 2.

Classic symptom of worn or blocked pump.

Do you guys/girls agree that if it doesn't get any better or cure the problem.......I may have to splash out and try a new pump?

Not without cleaning it and the rest of the system first.

 

[marcoslupo]

Guys n girls..
OK. Firstly many, many thanks for the time and advice that you have given me.
Over the weekend I'll spend some time getting the system as clean as possible (and remove the pump, HE and check all the gauzes for blockages) ..........and then add some more cleanser and leave in for some time. Do any of you have any recommendations as to the best brand to use?

If that STILL doesn't cure it.....then I'll look at shelling out for a new pump.

Just one other question.....
When I have the HE off, what is the best way to clean it? Softus seemed to think that putting mains pressure through it with a garden hose just aint gone do the trick. Should I sand blast it? Heh heh, Jus' kidding!
Once again, cheers to you all. I'll get you a beer when I see you at the bar.

 

[ACOperson]

- Remove plate h/e
- Blast mains water through it and shake out all loose deposits (this bit can take a while)
- Boil a kettle
- Add a few teaspoons of DS-3 & DS-40 chemicals & boiling water. Depending on whats in the h/e one or other or both of the chemicals will have effect.
-You may have to repeat the above process a couple of times, then flush with more mains water and keep shaking all the bits out.
- Make sure and flush all the acid out properly.

 

[fitz1]

could be lazy pump

 

[marcoslupo]

Phew..
Hi again.
Have been busy with this problem since the last post from fitz......Am pretty sure that the system is now 'clean'. Unfortunately, the problem is now getting worse. here's the latest symptoms:
High temp cutout is still 'tripping', but it only does it after the hot water (domestic) has been on. Basically, CH is on......I run hot water for a few seconds.....I turn the hot water off.....2 mins later when the CH cuts back in I hear a 'whooshing' sound come from the boiler.......the temp readout goes up....and the High temp threm cuts the system out. I'm also losing pressure in the system (from the PRV).
I seem to be getting a fair bit of air in the system too (rads upstairs need bleeding every week).
Anymore advice would be greatly appreciated.