Flushing CH with coal boiler

[AndyN01]

Hi all,

First post but thanks for all the brilliant advice I've been piggy backing in the past.

Not too sure if this is on the right forum - if not can a moderator move it to the right one - thanks

I have a coal boiler - Trianco 45K BTU heating the central heating only.

CH is "normal" pumped open system with 7 rads, F&E tank in the loft.

There's a gravity loop (28mm F&R) to keep flow through the boiler with an open heat sink rad (no lockshields TBOE).

System has been in several (many?) years. Rads have been taken off and flushed out (loads of black crud - lovely! At least it's not all over the carpets).

This is where I'd appreciate your help.

Planning on running X400 for a couple of weeks (longer?) with the boiler fired up and heating on.

Obviously, because it's a coal boiler I can't just turn it off but I can rake the fire out.

Is it better to drain the X400 out hot? Does that help or doesn't it matter if it's cold?

I'll wait for the boiler to cool (don't want to hit a hot cast iron boiler with cold water :wink5 before refilling the system with plain water then draining down (once? twice? more?) then refilling with X100.

How does that sound?

Thanks.

Andy.

 

[MC_Bob]

I've always drained a few times after dosing with chemical. And as a home owner you could do it a couple of times at your leisure.
Hot is normally better drained, but I think with your boiler I'd prefer to let it cool before draining to avoid rapidly cooling it.

 

[chris watkins]

Hi Andy & welcome along, now you have made your first post hope to hear more from you.

I am no expert in solid fuel boilers but done a fair bit of flushing in my time and what you are proposing sounds fine to me.

X400 is a strong cleaner so just make sure there are no leaking pipes /joints personally I wouldn't leave it in any more than a week or two weeks bare in mind the extra running time & likely hight temps over a normal gas / oil system.

Drain it warm maybe but more important don't let the circulation stop so the crud settle out, keep it moving until the last use the stat or wire the pump direct.

What are your drain offs like ? I would recommend a couple of line size valves one on flow & one on return or drop the index rad & drain through that.

Leave the float valve on to the F&E least until the draining water runs clear then turn it off drain right down before filling up.
I would do this at least twice or until the water draining runs clear first time then add X100.

 

[AndyN01]

Thanks both for replying so quickly.

MC_Bob

Letting it cool sounds like a good idea. Wasn't too keen on undoing the drain with seriously hot water but was just worried about if the X400 wouldn't hold all the muck it had suspended if it was cold.

Chris
Hadn't thought of putting extra line size drains in or letting it keep running through. Shall keep a good check on joints etc.

Cheers both.

 

[Best]

Hi Andy. I often used to drain the systems and remove each rad to outside and flush each one using a garden hose. Really cleans the bottom of rads well. But you need another person to help you and risks drops of black water on carpets.
You could however also flush the mains water through from a rad valve and out through the other valve using two hoses. This gives the pipework a good wash.
Your system shouldn't be full of magnetite if good inhibitor had been used from the beginning.
Be careful that your system isn't boiling up the vent, particularily as you say there is no hot cylinder

 

[AndyN01]

Hi Ben,

Thanks,

No idea if the system has ever had inhibitor in it. Judging by various bodge ups throughout the house in general (things like the flashing on the chimney not being turned into the brick courses at all :32 I'm doubting it.

No signs of boiling back up the vent but I'll keep an eye out - thanks for the heads up.

Andy.

 

[joni os]

If cleaner has been in system for couple of weeks then draining cold will be ok provided circulation is maintained prior to draining. Wire pump direct as Chris suggests above, but don't let pump run dry after drain down.

 

[AndyN01]

Thanks Joni,

It was the X400 going cold and not holding the gunge in suspension that was my main concern.

Now that look OK thanks for the heads up about keeping the flow going but not lettingthe pump go dry.

Cheers.

Andy.

 

[jtsplumbing]

Why not power flush it ?? you can hire a unit to do it !

 

[AndyN01]

Thanks for that.

Andy

 

[AndyN01]

Hi all,

Thanks for all your help and suggestions

Flushed through with the pump running at the weekend - water was a light brown colour with an odd few tiny bits in it. Flow took about ½ hour to come completely clear. Filled and emptied a couple of times to make sure the gravity system was clean as well. All now refilled with X100 and working quietly and we have a lovely warm home.

Thanks all - much appreciated

Andy.

 

[chris watkins]

Thanks for coming back and lettings us know how you got on Andy.

Glad it is all now working.

One good turn & all that, it's how the world should go around.