CH pump running constantly - sticky l/s(?) - sludge related?

What boiler do you have? Do you know if the boiler has pump over run?

 

Power flushing is quick way to make a lot of money & isn't always the solution to the problem.

Manual flushing also isn't the best option,better off fitting a magnetic filter lke a Magnaclean Pro 2 , plus add some cleaner like Adey MC3+ or Sentinel X800 & let it run around the system for a week, more effective & will collect any crud disloged by the cleaner.

You only need to look at the various threads on this forum for peeps with similar problems.

http://community.screwfix.com/threads/power-flush-options.185243/

http://community.screwfix.com/threads/diy-powerflush.185238/

 

A elderly boiler, pretty sure you would leave some crud behind, how much I don't know.but there a lot of knooks & crannies where the heavy crud can settle & when you drain the system it will get left behind.

As to limit switch on a diverter valve I don't know,not familar with that boiler, but I suppose crud could prevent the diverter valve to operate correctly, causing it to stick.

 

What model is the ideal boiler?

 

Boca, did you drain down, refill and flush and refill and flush the system after the X800? Or is it still in there. Along with all the carp it dislodged?

And is this diverter valve one of these: or is it built-in to the boiler?

If it's an external one like in the pic, then a good test is to turn orf the CH and if the pump is still running give this valve a good thump with summat hard but soft. See if the pump turns orf.

When you say the pump was still on, was the boiler also on? (Strange to have chust the pump running by itself...)

 

That was my thoughts unless the boiler has pump overrun in which case the pump will be connected to the boiler rather than the orange of the valve.

 

In which case would that discount it being stuck valve?

 

Yeah and would lead you to think a component within the boiler like the over run thermostat. I asked the op the model of his boiler to see if it does have pump over run but no reply.

 

Hmmm, so why wasn't the boiler running as well? Unless it had achieved max temp and the burner had shut down?

Anyhoo, see how it goes, and when it goes faulty again - as it very likely will - then thump it again. If that 'fixes' it again, then I think you've found yer issue...

 

That's the mystery, boca.

The way your control system works - should work - is that your Timer (programmer) first says "It's time to come on". That timer then sends its ON signal to the room stat (or cylinder stat for hot water) which says "Yup - it's chilly so the boiler needs to come on". The stat then sends that ON signal on to the motorised valve which moves in to the right position (CH, DHW or the middle for both) and trips a wee microswitch which then sends the ON signal to the boiler and pump. Which should then come on...

Each of these components cannot turn the boiler/pump on by itself - except for the motorised valve, because that component has it's own power supply. So if you were to manually move the motorised valve in to a CH or DHW position, then it could turn on the boiler/pump even tho' the timer said "NO!" and the stat "DITTO!"

So that is why suspicion falls on the motorised valve, one with sticky microswitches or other bits inside.

However, it is a mystery to me why it ONLY gets the pump running and not also the boiler.

Hey-ho. That's my understanding anyhoo.

Keep an eye on it, and be ready to thump it again if needed. Monitor whether this sorts it again. If it does, then I think that's pretty conclusive.

 

Thanks for the update - that's good news

As for draining, you don't chust want to get rid of the chemicals, but mainly all the sludge that's now in suspension.

Have you fitted a Magnetic filter at all? If not, I really think that's a big mistake - the cost is minimal and the benefits long-term.

What's more, you could then do what I do when it comes to flushing oot ma system: I remove the Magnaclean filter and attach a couple of 3/4" BSP male fittings to the valved connectors left on the pipes (I use washing machine valves for this as they are the right size but also they also have valves on them so I can shut off the flow when I disconnect them) to which are attached garden hoses. The 'return' pipe from the rads goes ootside (in to a bucket so's I can observe the water colour) and the 'boiler' side goes to a garden tap. I set it running until the water runs clear - yes, this takes a while.

The weird thing is, when I've finished this flushing and shut off the valves again, I find my pressure is still around 1 bar!

No bleedin', usually no topping up - and a completely clean system.

 

I like this idea! Just fitted a Magnaclean 2XP to my system last Friday. No additional chems added yet. Will need to chem'n'flush at some point but don't fancy a full drain and refill as my system is <cough> "interesting". Hadn't dawned on me I could engineer a constant flow using the filter connections. Will need to keep an eye on header tank mind!
Will investigate as think my filter connections are a little larger than 3/4"!!

 

You're a bloomin genius.

 

3/4" fittings are physically quite big - more than you'd imagine - so chances are that's what they are. Compare them with a W/M hose connection - that's 3/4" BSP.

Ah, you have a vented system? Even easier to flush, then - it's as you say. (I wouldn't suggesting hosing it through like a sealed system simply 'cos I've no idea where the water would go!)

Yes, all you'd need to do is to open a drain cock at your lowest point - ideally you should have two of these, one on the flow pipe run and one on t'return.

Then chust keep an eye on your header tank to make sure it doesn't empty after a while and draw in air. If you find it's emptying too quickly, then simply close off the drain cock a bit.

Repeat on t'other 'cock. I think that would be enough to gently flush through the rads too. If you put the hose end in a light-coloured bucket, you can quickly monitor the water colour - it'll almost certainly start of dark brown.

But, really fit a Magnaclean regardless.

 

Yes, but this forum is for telling people things they didn't already know...