Change rad size - Easy way?

[Ccw71]

Hi all,

I'm going to be changing all 9 of my downstairs radiators which are about 40 year old type 11, to larger sized type 21 bought super cheap in clearance last year. I have an open vented system and no immersion heater, so want would like input on what is the most logical way to go about it. I would want to keep the system filled for as much as possible with shortest possible drained down period, so we have hot water.

I want to do it as much DIY as possible, but could get a plumber in for a day if it makes sense. The options as I see it are:

Adjusting the pipework first (using push fit) then shutting off the valves and refilling. This would mean super accuracy required in both the pipework and then later hanging the rads in the correct position. I'm not even sure it would be possible?

Shutting off valves, remove old and hang new rads, then getting a plumber in to adjust the pipework after would seem the most efficient way to go. However hanging the new larger rads first may not be possible as the pipes will be in the way?

Any advice would be appreciated.

 

[lostinthelight]

If it were me and because I like to take my time I would look into isolating the the heating flow and return so I could still use DHW side...assuming not an uncontrolled heat source .

 

[Ccw71]

I have a heat only boiler on an S-Plan system. I'm not sure there's a way to isolate the heating side as they share the return? I guess gate valves could be installed on the heating system flow and return, but that would be a job in itself and possibly restrict the flow?

Any other ideas?

 

[oldbutnotdead]

Invest in a couple of 22mm ball valves- not cheap iso valves, the nice full- bore ones with levers.
Drain down.
Fit valves in flow and return of the heating leg (make sure you don't accidentally isolate feed and vent pipes)
Close valves
Refill (dhw) bit of the system, make sure its running ok.
Take your time with the rads.
Either learn to solder or get all the old rads off, new rads fixed in position and then call your plumber.

 

[Ccw71]

Thanks. When you say "invest in"...is there a particularly good valve you'd recommend?

 

[Ccw71]

Hmmm, more investigation required. I've just had a look and found easy access to the CH flow after the pump and 2 port valve, but only 1 visible return, which I'm assuming means the CH and HW returns merge under the floor somewhere before returning to where all my other hardware is located.

 

[Laurieo]

Have you not got an immersion heater you could switch on for a few days ?,rather than put yourself under pressure.

 

[Ccw71]

I don't, but even if there was one, I think I'd still need some way to isolate the two systems to allow me to drain down the heating side.

 

[oldbutnotdead]

Pegler are a solid bet. About £10 each at Toolstation/Screwfix at the mo.
And that's boring. Might be time for a bit of floorboard lifting....

 

[oldbutnotdead]

I don't, but even if there was one, I think I'd still need some way to isolate the two systems to allow me to drain down the heating side.

If you had an immersion heater you would be fine with draining the primary (heating) circuit and leaving secondary (dhw) full and running. But you are where you are ...

 

[Ccw71]

Would I be able to just drain, cut the rad pipes to just above floor level and cap with push fit end stops, then refill? Would there be any problems with doing this?

I could then hang the new rads and get a plumber in for a 2 or 3 hours to adjust the pipes for the 9 new radiators.

Does 2 or 3 hours sound enough for a professional plumber? The pipework is under a suspended timber floor, 3.5 foot void with access hatches already cut in each room.

 

[oldbutnotdead]

Would I be able to just drain, cut the rad pipes to just above floor level and cap with push fit end stops, then refill? Would there be any problems with doing this?

I could then hang the new rads and get a plumber in for a 2 or 3 hours to adjust the pipes for the 9 new radiators.

Does 2 or 3 hours sound enough for a professional plumber? The pipework is under a suspended timber floor, 3.5 foot void with access hatches already cut in each room.

You could, but if access is that easy you can get a valve in the heating return. Placcie stops will add a few quid to your budget (the nice removable JG ones are at least a quid each). Decide now, by the way, whether you want pipes coming straight up from the floor or can you live with/have you got space for a dogleg? If the latter then leave as much vertical coming up through the floor as you can when you cut and cap.
Drawbacks of your plan- there'll be water in the pipes so soldering will take a bit longer cos of drying out and faffing.
3 hrs for 18 bends/joints is 10 minutes per which might be ambitious (not a pro plumber myself so might be massively wrong there).