a blocked cold feed/cure?...

[liverpoolboy]

if for eg your top rads when bled don't disperse any water and are cold at the bottom you are likely to have a blocked cold feed i believe. is a good way of curing this by: flushing then system through and cleaning down the cold feed with a long rod to move/budge any sedimenet, etc...? or is replacing pipework the only thing to do? i am curious ..........

 

[seco services]

depends on the blockage, pipework etc.
many i have cleared by just using a chemical, some i have cut out, some i have cleared with mains pressure.

 

[plumbnuts]

The cold feed is most likely to be blocked at the H piece of pipework where the vent and cold fill meet.

 

[liverpoolboy]

Hi-there

to return to my post from a few days ago. What cleaner / chemical cleaner can be used to clear the cold feed? Also though will this not just mean that the crud/sediment will then be circulating around my central heating/primary pipework?

Does bleeding the top rads and them not releasing water with pressure mean I do have a good chance of a blocked cold eed from my F&E tank? Should this water also be black or does this not matter ...

Thank you for helping/advice.

 

[seco services]

you can use one of the sentinel chemicals
http://www.sentinel-solutions.net/en/heating/X800/application

follow the instructions and use after refilling
http://www.sentinel-solutions.net/en/heating/X100

over time if your f/e is not filling system the top rads will not bleed at all as the water level in system will be to low.
and in the end the pump will be starved of water and seize.

 

[liverpoolboy]

thank you seco for your advice and help.

will this also work if the blockage is in the actualy air separator? i guess it should?

 

[ChrisR]

See wot I rote: //www.diynot.com/forums/viewtopic.php?p=771846#771846

If the blockage is hard, no chemical will shift it, you have to
1) push something like a thin drain spring up the pipes to break it out, or
2) cut the pipe out and replace it.

A bit more here:
//www.diynot.com/forums/viewtopic.php?p=891831#891831

 

[seco services]

i've had it work in air seperators.

 

[steved101]

best bet may be to replace affected pipe. as this way you don't risk any of the muck circulating around your system, if you do manage to poke it free!

 

[ChrisR]

If you're doing the drain spring thing, which often works very well, you can often access via the pump valves, downstream as shown in my second link, where you can collect the carp.

 

[steved101]

good point and good idea. undoing the pump unions though will probably mean needing new gaskets / washers for the pump when re-tightening though I guess?? I doubt the same ones will seal 100% again...

 

[Softus]

Does bleeding the top rads and them not releasing water with pressure mean I do have a good chance of a blocked cold eed from my F&E tank?

You're immediately off down the wrong road if you're worrying about likelihood when all we have is your description of the symptoms.

You just have to work through the problem, eliminating the easiest things until you find the cause. And there might be multiple causes, because Magnetite and rust get everywhere.

Once you've cleaned any/all muck from the F&E cistern, refill it, then, with its supply shut off again, drain 4 gallons out of the lowest drain off cock and see if the F&E empties.

If it does, you don't have a blocked cold feed and you're worrying about it for nothing.

Notwithstanding that, you're headed for a full drain down anyway, since you have multiple rads with cold spots at the bottom.

Should this water also be black or does this not matter.

WTF do you mean? Is the water black or not?

 

[steved101]

Get someone to stand in the F & E while you empty a bit from a low drain off valve. THEN if you discover it is not a blocked cold feed, it must be sludge, etc built up in the system as it has affected more than 1 rad. SO you will need to drain down and add a cleaner to the F & E cistern on re-filling. Also flushing through each rad is a good idea!

A blocked cold feed is dangerous as the "feed and expansion pipe" takes up the expanded amount of water when heated, so if you have a close coupled layout the vent pipe pumping over should cater for this, and also this will be another sign of a blocked cold feed!

 

[Softus]

..

Two good points, and well made.

 

[liverpoolboy]

the reason I said about the water being black is because I read an older post on a similar matter a while ago and I think they meant if the water is black then it is the old dirty(ish) CH water. DOn't know if this makes any sense to you?