Draining central heating system - UPDATED Q PLEASE

aliasojo

NEW QUESTION:

Forgive me if this is a stupid idea or question, I'm happy to admit there's something I'm not seeing or not understanding......but is there a reason why, instead of draining down the system to get rid off the cleaner and dirty water and then refilling it, I can't just turn on the tap on the filling loop under the boiler and let the water flush through the system continuously, coming out through the open drain valves?

That way, I'd lessen the potential for airblocks and I'd not need to open all the air valves on the rads?

That seems too simple, there must be a reason why I can't do it.

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For some reason, when my boiler and central heating was installed, there were no drain points included. I didn't even know what a drain point was in those days so didn't know to query this.

A few years later, a different plumber came to change a radiator and whilst he was at it, he put in a (as I thought) drain point.

I now need to drain my system (need to add cleaner, re-drain then add inhibitor) and I find I have 2 drain valves.....I'm not sure why or which I should open? Or do I need to do both?

They are both joined to pipework just under the floor.

Question 1: Does it matter which one I join the hosepipe to?

Question 2: Both valves are maybe a foot under the floor. The edge of the floor is maybe 8 inches from the valve (just a little beyond the bottom edge of the picture). Will it still drain ok if the hose comes up over the floor and out the door? I have no way of getting it outside if it has to be under the floor and lower than the valve.

I could lessen the gradient by letting the hose coil loosely so it gets slightly higher with each coil rather than making it come up directly over the floor straight from the valve. If that makes sense?

Please...no comments about the state of the cables under the floor. I am now well aware of how things should be, but unfortunately it has taken years of interacting with poor tradesmen before I finally found some good ones. By then a lot of services (and their lazy workmanship) were already in place.

I'd be grateful for advice, I have never drained or refilled a system before and whilst I'm sure it's not rocket science, I'd like to do it as properly as possible.

anotherbaldrick

Drain from both and open the vent plugs on the top of radiator and towel rails. You will have to bring the drain hoses over the floorboards to remove most of the contents and perhaps catch the remainder in a tin .

heretohelp

Are your copper pipes covered in plastic or as someone just jammed plastic pipe onto the ends of the copper pipe?

aliasojo

Plastic covered.

heretohelp

You learn something every day (sometimes) have seen copper gas pipe with yellow plastic on it but not water pipe.

Mr_Ted

Mmmmmmm confusing?

Do you have underfloor heating?

If so, or even worse if not, the manifolds are NOT usually under the floor?

If not, why manifolds at all?

You will need to open both, particularly as with the type of pipework there are likely to be undulations, and if there are you may have a problem with airlocks when it comes to refilling

Drain as much as you can to outside with a hose and open radiator bleed valves as water drains starting from highest radiator(so that as level drops water wont come out of bleed valve into room) to lower radiators, but as water only finds its own level, you also need to drain the lower parts of the pipework also, either into a container of some sort via a short length of hose under the floor, OR if its a ground floor and not to much water left in the lower pipework you MAY get away with just letting it go under the floor as it will most likely drain away or just evaporate in a short period of time, but thats dependent of the ground under the boards and the actual amount of water?

Would be interesting to know exactly what type of system you have, radiators or underfloor heating, open vented system(tanks in roof) or sealed system, and type of boiler and cylinder?

ALSO if in doubt, get someone out, who knows what he's doing

aliasojo

heretohelp wrote: »

You learn something every day (sometimes) have seen copper gas pipe with yellow plastic on it but not water pipe.

I've found there seem to be regional differences between materials most commonly used.

I remember posting years back about the 'facings' that went round a window. No-one had a clue what I was on about at that time yet it was absolutely the norm for houses in the Highlands to have wood architrave round them the same way a doorway would.

People in England thought I was daft.

I wonder if this is similar? The pipes used in my house are the norm in these parts.

aliasojo

Mr_Ted wrote: »

Mmmmmmm confusing?

Do you have underfloor heating?

If so, or even worse if not, the manifolds are NOT usually under the floor?

If not, why manifolds at all?

You will need to open both, particularly as with the type of pipework there are likely to be undulations, and if there are you may have a problem with airlocks when it comes to refilling

Drain as much as you can to outside with a hose and open radiator bleed valves as water drains starting from highest radiator(so that as level drops water wont come out of bleed valve into room) to lower radiators, but as water only finds its own level, you also need to drain the lower parts of the pipework also, either into a container of some sort via a short length of hose under the floor, OR if its a ground floor and not to much water left in the lower pipework you MAY get away with just letting it go under the floor as it will most likely drain away or just evaporate in a short period of time, but thats dependent of the ground under the boards and the actual amount of water?

Would be interesting to know exactly what type of system you have, radiators or underfloor heating, open vented system(tanks in roof) or sealed system, and type of boiler and cylinder?

ALSO if in doubt, get someone out, who knows what he's doing

I have a Worcester Bosch Greenstar 35CDi combi boiler. (Discontinued April 2007 apparently.) Sealed system, no tanks. Radiators throughout house. Electric underfloor heating in bathroom.

System was drained under the floor once before and it evaporated but I would really prefer to get most of the water outside this time. I wasn't happy about the amount of cables lying on the solum that must have been affected because of the draining.

Airlocks are a concern. Any advice on how to try to avoid/deal with if they happen?

Btw, the manifolds enable each rad to be connected individually. There's another upstairs where the upstairs rads are connected to.

Mr_Ted

aliasojo wrote: »

Airlocks are a concern. Any advice on how to try to avoid/deal with if they happen?
Btw, the manifolds enable each rad to be connected individually. There's another upstairs where the upstairs rads are connected to.

As its a sealed system you MAY get away with refilling, but I doubt it, in which case it will either be necessary to bleed radiator often and top up system until all the air is out, another possibility is to back fill from the drain points slowly which will need 2 people, 1 to watch the hose connection and another to dash round the house closing rad bleed valves as they fill, also to make sure system does not over pressure

As for the pipework, the way it has been done must have been expensive as hugely excessive amounts of pipework will have been used compared to conventional circuits :eek:

anotherbaldrick

microbore System ?

http://www.heatandplumb.com/acatalog/10mm_PVC_Coated_Pipe.html

Mr_Ted

anotherbaldrick wrote: »

microbore System ?

I would say Mini bore as micro would be 6 or 8 mm

Admit at 1st glance, probably due to perspective in piccie that it was 15 mm soft copper pipework, or aging sight :rotfl:

Either way same problem with possible airlocks due to the difficulty of not having straight pipework that you would with conventional small bore

And would stick by excessive pipework requirements on this type of system compared to conventional