Replacing a radiator with a larger one in the same location

[Participant]

Hi all

I'm looking to replace the 1000mm double panel double convector rad in our master bedroom with an 1800mm 2x2, because the room is always slightly colder than the rest of the house. This should increase the BTU potential in the room by c.4k.

Part of the reason for the room being cold is insufficient insulation in the void between garage and bedroom, which I'm sorting, but another aspect is the radiator being too small for the size of the room. 1800mm is the largest rad that will fit in the available space.

I can access the pipes through the floorboards and have drained down a heating system before, so am thinking of having a go myself. My only concerns are:

- How much difference will 4,000 BTUs make and therefore is this worth £120?
- Is the job as simple as extending the copper pipes under the floor boards to the new locations and bringing them up through the floor, before connecting to the rads...feel this sounds too easy and not sure if I'm missing something
- My new system is unvented; does this affect the process for draining the system, i.e. switch the boiler off, drain through drain tap on ground floor, open bleed valves in all rads, adjust pipe work, add inhibitor, final connections, refill, bleed?

Thanks.

 

[varial]

Should be fine... Fit tvr to help get a stable room temp. If it's copper you can still use push fit fittings just make sure to file any Sharpe edges before pushing into the fitting. My tip is fit the rad to the wall with all fittings not forgetring a good use of tape on the joints. Then put some copping tails down from the valves and connect up to them. Posted on phone hope makes sense and helps

 

[NickK]

You may want a TRV on it.

I'e replaced a ~2BTU and a 1.5K BTU in the same room (kitchen/diner) with an 1800x590 twin 6700 BTU radiator with a TRV (~£280). I've also replaced the bathroom rad with a 1600cm radiator too.

There are 'recommended' values based on dimensions of the room for kitchen (3500 BTU in our case) and Dining room (4500 BTU). As our open plan kitchen spans the dining room having this boosted offers both the option for cosy and the TRV copes with additional people and cooking heat.

The 1800 rad was 45kg dry.. and came four double bolt mounting blocks. You can feel the radiated heat from several meters away. Just make sure you have all the bits - including installing a air valve and etc for the rad.

We have a Bosch Worchester 32cdi 24kW (81K BTU) max and there is another 6700 BTU rad in the front room area. We have three normal bedroom rads and a 1600cm towel rail rad in the bathroom.

Fitting extension piping for the bathroom rad was something I had to get used to - I soldered the extension in-situ and it can be difficult to get the positions and not set fire to anything (even with a heat mat and a slender MAPP flame). If you solder you'll need a decent torch, emery cloth, flux, solder and copper pieces, however you could possibly get push fits. You'll also get water cooling the joint in the pipe etc. So for your first.. better just drain it if possible.

Yes you can replace a radiator with minimal water loss but given the size and the location if it's your first you may want to drain for safety. I switched off the the boiler, closed the CH & HW valves and then drained out some water still. However you may/may not be able todo this - it depends on your system setup.

Once fit the rad will make a fair-sized water drain on the CH, so keep the boiler off when you first fill it as you may need to add more water.

The main thing is getting your valves level and having the measurements accurate - you'll want to fit the mounts then the rad.. Also do you have all the rad valve bits you need - I switched from a hex key style to a more modern external style.

Oh - and learn how to fit the PTFE tape the right way around the thread - I had to drain and reseat the valve due to a very small leak due to the PTFE being on the wrong way on the thread into the rad itself.

 

[ANDARIAL]

Maybe get some pipe thread compound to apply to the screw in bits and also if you drain down remember to refill with additive like sentinel

 

[Participant]

Thanks all, some useful thoughts.

I'll be using PTFE (wound with the thread direction!) and copper push fit for under the boards.

My main concerns are how to drain down an unvented system but it sounds like it's no more complicated than any other system.

I was not aware of any requirement for new rad valve bits so will look into this.

Thanks.

 

[NickK]

Oh - you can feel that the system is slower to warm up from cold start too. Just the nature of the beast - adding what is about 4K BTU in radiator will result in colder water down stream of the radiator valves are left fully open.