Problems with small bore pipe and an old central heating system

[jh2254]

Can,t open attachment but its normal for only a dribble to come out of the vent screw.

Just remove the pump head and have a look inside.

OK thanks. I also opened the top and bottom valves and still only a trickle? Is this normal? Also I was a little worried that the magnet stuck like glue to the copper pipe just to the left of the bottom valve - does this show that its full of magnetite?

 

[John.g]

Yes, its quite normal for only a dribble to come out of the vent with both valves open as the end of the pump shaft is inside this vent plug.
You will either have to remove the pump complete or for a start just remove the pump head (far easier) to check for magnetite build up or whatever.

 

[ShaunCorbs]

A magnet shouldn’t stick to copper so yes blocked

 

[jh2254]

Yes, its quite normal for only a dribble to come out of the vent with both valves open as the end of the pump shaft is inside this vent plug.
You will either have to remove the pump complete or for a start just remove the pump head (far easier) to check for magnetite build up or whatever.

Tried to remove the pump head only by trying to crack open the 4 bolts. First bolt I tried would not budge using a small allen key. Then put a set of mole grips on and tried. Still did not budge. Should I use full force or is that likely to shear the bolt head? Just thought I would ask in advance! Surely it should not take that much force? Thanks.

 

[ShaunCorbs]

Undo the unions ?

 

[jh2254]

Undo the unions ?

Yes I could do this but I really wanted to clean the fins inside and see what magnetite was in. Will give it another go and if no luck I take off the unions. Thanks.

 

[John.g]

A bit of pipe on the end of the allen key might budge it, drop of release oil or wd40 first?.

 

[jh2254]

Success! Attached are the before pictures.
What is the best way to clean off the magnetite? Also opened up the top and bottom unions and clear water came out. Once the magnetite is cleaned off will the pump have increased power or not? Thank you.

 

[jh2254]

For instance do I soak in X800 ? Thank you.

 

[ShaunCorbs]

Looks clean it will be black just make sure the holes / fins in the impella are clear

 

[John.g]

Unfortunately!, the pump impeller looks very clean, get a tie wrap and shove it it through each vane in the impeller (right hand picture) to ensure each one clear.

 

[jh2254]

Unfortunately!, the pump impeller looks very clean, get a tie wrap and shove it it through each vane in the impeller (right hand picture) to ensure each one clear.

OK thanks. Looks like the two magnacleans I fitted on the flow pipes to the small bore pipes is working! I am a little worried that the magnet stuck like glue (see large magnet) but perhaps I dont need to be worried as when I opened the bottom valve water flowed?
Also if I put x800 in the system for a few weeks would that help with the baked on magnetite in the copper pipe and any remaining in the small bore? If not then I may just have to live with the small bore rads at the end of the system taking an hour to come on? Thanks.

 

[John.g]

Can you post a picture of the Grundfos pump label and should then be able to figure out if a 5M or 6M pump, also, it should give the rating of the capacitor inside the terminal box, probably, 2.4uF, some say that when these start getting weak that while they will still start the pump but it will run slower and produce less head, you can also test this capacitor with some multimeters, might be worth renewing if one can be picked up cheap, otherwise maybe consider something like a DAB Evosta 3 for ~ £120.

 

[jh2254]

Can you post a picture of the Grundfos pump label and should then be able to figure out if a 5M or 6M pump, also, it should give the rating of the capacitor inside the terminal box, probably, 2.4uF, some say that when these start getting weak that while they will still start the pump but it will run slower and produce less head, you can also test this capacitor with some multimeters, might be worth renewing if one can be picked up cheap, otherwise maybe consider something like a DAB Evosta 3 for ~ £120.

This is it. I think its 6m? Is it worth running through some x800 for a few weeks to clear the film of magnetite in the system? Or is this not worth it? Thanks.

 

[ShaunCorbs]

If a magnet sticks x800 might help but won’t do much if it’s 1/2 restricted

 

[Ben-gee]

Use your magnet to investigate extent of blockage, depending on what you find- cut out and replace that section of pipe

 

[jh2254]

 

[jh2254]

Update. Central heating has now been running ok for the last few weeks with X800. Every few days I have been cleaning out the two magnacleans I installed. Last time was today after I left heating on timed (one hour in the morning and one hour in the evening) for the last 8 days. It collected magnetite as per the photos attached. Should I leave the X800 in for a few more weeks until it collects no more magnetite or drain and fill with inhibitor now ? Many thanks.

 

[jh2254]

Update. Now into December and with the X800 still in system I continue to collect weekly amounts of magnetite. See pictures. When is the right time to drain the system and add x100 ? Many thanks.

 

[jh2254]

Update (October 2023). System still running perfectly. I drained down in the summer and put new inhibitor in. Recently powered up and the central heating is running well. Still collecting the debris in the 2 magnacleans I fitted at the troublesome spots on the system (entry into the small bore pipes leading to the radiators that did not heat up) but I dont mind cleaning them out every month. Rather this than spend £2k on a power flush that is not guaranteed to work and may cause no end of problems on my 40 year old multi pipe (normal and small bore) system! Learnt a lot on this forum and if I had my time again would not have allowed these so called 'professional plumbers' to install small bore pipes in my system!! Thanks again. Cheers.