Circulating pump problem

[Aragorn84]

My brother is having some trouble with his heating. Its an open vented system with an Ideal Classic FF250.

He came home the other night to various gurgling noises coming from the pipework, and a number of radiators seemed to be partially cold.

He bled the radiators and found lots of air in them, which bled out successfully. After that the gurgling stopped but the pump was making a ticking noise. The boiler didnt seem to want to fire up.

He turned it all off and left it for a while and tried it again, at which point the boiler started fine, ran for a short time, perhaps 30 seconds, then shut down. The pump continued making the ticking noise.

I suspected the pump had failed, the symptoms were similar to what my parents boiler did a few years back, same model of Wilo pump, so i suggested he replace it.

Hes done that this evening and put everything back together, but the issue remains. New pump doesnt tick, but the boiler starts for a short time then shuts down again. Pump sounds a bit gurgly/bubbly and there doesnt appear to be the usual "running water" sound at the radiators.

Everything seems to be pointing to a circulation issue, but if its not the pump what on earth is going on?

 

[picasso]

Has he bled the pump and pipework ?

 

[Aragorn84]

He says theres water coming out the pump when he opens the bleed screw, but only when the pump is NOT running. When its running, nothing comes out. Maybe thats by design.

He also says hes bled all the radiators. Not sure if hes bled the hot water coil.

Theres a pair of zone valves but they seem to motor open correctly and turn the pump and boiler on.

 

[hazetimesfive]

water in the header tank?

possibly blocked cold feed.

 

[Aragorn84]

There is water in the tank, but he also said theres a lot of silt in the bottom of it... i wonder if the silt has been drawn in when hes bled the system and its caused a blockage somewhere?

Any thoughts on what to try next? I guess some sort of flushing process?

 

[hazetimesfive]

do all the radiators have water coming out when you bleed them? does heat leave the boiler when it's running? how far does the heat get?

 

[Aragorn84]

I'm going over tomorrow to have a look.

He said the pipes out the boiler were cold, but the boiler itself appeared to get hot.

 

[FiremanT]

Take a magnet with you. Search this forum as to why

 

[Aragorn84]

Magnet made sense and sure enough the filling loop and nearby pipework was very magnetic.

Cut out a couple feet of pipe, cleaned out the pipe run from the F&E tank and rebuilt the pipework with new pipe and got it all working.

Quick pic from todays efforts:

https://www.dropbox.com/s/8w6lpra4tqeuxp9/2016-03-06 15.16.51.jpg?dl=0

Cut the pipe from the F&E tank, which was half full (had bailed out half the water), not a drip coming out of it at this point. Bit of fishing with some electrical cable shifted the blockage and got a nice strong flow of water down. Emptied the F&E tank completely, cleaned out all the sludge and sorted the pipework with new.

After:

https://www.dropbox.com/s/0005dh3wt24f0ln/2016-03-06 16.59.56.jpg?dl=0


Put a Sentinel X400 treatment into the system when putting it back together, so hopefully that will clean it out a bit. We will drain it out in a couple weeks and refill with inhibitor.

I wanted to convert it to sealed, but my brother wanted it working with minimal faffing.

Cheers for the help!

 

[hazetimesfive]

good job getting it fixed, however I would change the loop, have the cold feed teeing in above.

 

[Aragorn84]

The existing install with the inverted loop appears to be as per the boiler manufacturer instructions, so we just left it like that.

I was thinking about converting it to a sealed system. You can buy the expansion vessel and PRV kit for about 40quid, and would do away with the F&E tank and i imagine reduce the possibility of a repeat of the sludging up...

Thoughts on that? The boiler instructions suggest its suitable for use with a sealed system, so no issue there. I guess theres a concern that it might cause leaks with the increased pressure?

 

[hazetimesfive]

There is nothing wrong with open vent, I've never like inverted cold feeds especially as your system is dirty.

Sealing it is more work than its worth, there is no real benefit but a risk or two.

 

[Aragorn84]

Isnt the whole idea of the sealed system that your reducing the available oxygen and thus making it less likely to get sludged up?

Given it needs drained down anyway to get the X400 out it doesnt seem like a huge job to remove the F&E connections and attach the vessel and associated parts.

Any new boiler in the future would be sealed anyway right?

I just felt given he was in the frame of mind of "fixing the heating" it might be a good idea to do some preventative maintenance and upgrades. Was also looking at the magnetic system filters as well.

Would you just leave it all alone?

 

[hazetimesfive]

There shouldn't be any circulation through the fne tank unless badly designed.

Magnetic filters are always recommended.

If you do seal don't forget the filling loop.

If it ain't broke and all that

 

[Aragorn84]

Yeh, i'm coming round to that. The header is now clean, so the work theres already done. Its lasted this long, so clean it out as best we can and ensure its properly dosed with inhibitor and hopefully that will keep it in decent fettle for a while.

Probably better spending the money on a Magnaclean than the sealed parts too.