Happy New Year friends!

I hope you had a great Christmas break. For us it was the first time in three years we've spent it with family which was lovely. As good was getting the lad in his bedroom before year's end. We're a bit behind in these newsletters so here are the last steps prior to plastering.

🪟 Window Board

In the other bedroom I added the window board after plastering, made the fit as tight as possible and caulked any gaps. However you get a better finish if you install the window board before and plaster around it.

I bought a pre-primed MDF window board the correct depth to give a little overhang and cut the two ends with my jigsaw for an overlap onto the walls of about 6cm. If your external cill has a little ledge like mine you can order a board with a rebate, though I had to deepen mine to allow it to be flush with the window.

Though it will get messy with plaster I decided to paint it now with a small foam roller as I can never get a great finish with a brush. Once dry, I attached it with grab adhesive and levelled it but first made sure the window was sealed as much as possible to stop draughts.

I bought from Skirting4U, and picked up my skirting and architrave at the same time but they're plenty of other options including wood or plastic cills, some of which are insulated which is probably a good shout - I may look at those when we eventually change the windows.

🌡️ A New Radiator

As it turns out, changing or removing a radiator is not particularly difficult but there are a few steps involved.

Choosing a radiator

In that pic above, you can see how close to the wall the radiator pipes are. This is of course because I've added about 6-7cm of wall depth with the insulated plasterboard. In the other bedroom I had just enough wiggle room in the pipes to allow me pull them away from the wall to re-fit the radiator, but not here. I'm going to have to move them.

Below is the original radiator which I still have. It matches the window width, which some think looks correct, is no doubt specced to the room size and it's not that old (a convection rad). If I re-used it I could get a pipe bender and bend the copper pipes to be further out from the wall, cut off the excess and be done with it.

However, in the other bedroom the radiator is smaller and looks better I think. It's 900mm wide but after taking the valves into account this width wouldn't work with in the kid's room as the floor joists are in the way of where the pipework would need to be.

To assess my options, I jumped on a BTU calculator. The variables don't allow for the one solid external wall and one insulated plasterboard wall but playing around with the options I reckoned I need around 4000 BTU. I searched through Screwfix for rads above this figure and settled on a double panel, double convection (type 22) 800mm wide rad which suits the positions of the joists. Has a BTU of 4666.

Of course, there other types of radiators. Column rads look good in period properties while aluminium rads are the most conductive and therefore responsive, but pricier than steel.

Heat pump viability

I try to future proof as much as possible. Once we extend to the side and make one of the room's external walls internal, we upgrade the loft insulation and the windows the room's BTU requirement will fall to around 2000 (or 586W). No problem, I'll just turn the TRV lower.

I think there's a good chance heat pumps will get better and cheaper in the long term so I want the new rad to be able to cope with the lower temp heat pumps provide (~50 degrees). Here's a helpful article to figure it out. The answer is yes, this rad is big enough, once the upgrades are made to work with a heat pump.

Cool. Or warm I suppose.

TRV and pipe positioning

The rad I chose came with a free set of TRV/Lockshield valve but by all accounts are rubbish so I bought this set instead. I did glance at the smart TRVs but I reckon the ROI is low plus we don't even have a smart thermostat yet.

I unpacked everything, attached the valves to the rad and measured across to get the distance between the pipes and marked them on the floorboard.

To get the distance from the wall, I consulted the rad's manual. To the middle of the radiator, there's two figures given depending on which way you have the brackets.

If you scroll back up to the pic of the master bedroom where my side of the bed is a bit constricted I turned the rad bracket to have the shorter side facing out so that the rad is tighter to the wall and I have more walking room.

It's a good option if you're limited for space, best paired with single panel/single convector rad.

However, for best convection of heat, the wider side of the bracket should be facing out to give you about 50mm of space between wall and rad. This is a figure I've talked about before as a minimum ventilation space under floor joists and in flat cold roofs.

Anyway, I then marked the distance from the wall for the pipes and cut holes wide enough for the pipes in the floorboard with my hole saw. I'm ready.

Draining the central heating system

I need to drain it at least below the level of the upstairs' floor. I turned off the heating and hot water at the programmer and found the drain-off valve. You'll find yours downstairs and often on a radiator like this:

Ours is not on a rad and instead is tucked away in a cupboard. I pushed a length of hose pipe on to the nozzle and secured it with a jubilee clip.

The other end of the pipe goes to the drain outside which, crucially if you're draining your whole system, is lower than than the drain off valve. I imagine if you are tinkering with pipes under the ground floor, lower than the drain off valve then you have to catch the remaining water in a bucket when cutting the pipes.

If you have a boiler fed from a tank then you'll need to stop water entering the heating system by tying up the ballcock or, if there is one, turning off the valve supplying the tank. Ours isn't.

I turned the drain-off valve to open to allow the heating system to drain out, which it will initially. However the negative pressure will start to build so we need to let air in at the top - a bit like if you were to dip a straw in water, place your thumb on the top and remove the straw, the water won't fall out the bottom until you remove your thumb and let air in at the top.

To do this we need to open the bleeding valves of the radiators upstairs and we start with the highest which is usually the bathroom towel radiator. Air will start to be sucked in. Then go to your next highest radiator and open that valve, and so on. If a bit of water starts to come out, you'll know you need to wait a bit until the water level has dropped. Here's the bleed valve on the other bedroom's rad. The little hole is where air enters/exits.

I had to guess when the water level was below my floor level. Going lower was fine of course but I didn't open the bleed valves of the downstairs' radiators.

New pipework

I could then plumb the new pipework with Speedfit as I've recently described.



Once complete I made sure the Lockshield was turned off and the TRV was set to the frost prevention setting. This will prevent water coming out when I re-fill the system.

Side note: I inadvertently tested the frost prevention setting when we had that cold snap. The window was open to allow the plaster to dry and a wet patch appeared! Good to see these things in action though :)

Now it was time to re-fill the system which just required opening the filling loop and closing the bleed valves in the reverse order i.e. lowest to highest.

Adding inhibitor

I turned the filling loop off just before the towel rail filled completely because I needed to add inhibitor to prevent corrosion and build up of limescale. To do this I removed the blanking cap (or bleed valve) from the towel rail which unlike the other rads is on top which makes pouring the inhibitor in easier.

I think you're supposed to do this once a year or so but certainly if you've drained your system as much as I have.

If I'd been doing this in summer and wasn't in such a rush I'd probably take the chance to power flush the system and sort out the Magna-Clean but it was cold and the plasterer was due in a couple of days so I didn't bother. A mistake I've made in previous rooms is not flushing out the radiators with a hose to get rid of any sludge before putting them back. Obviously this radiator is new so it's not needed here.

Attaching the radiator

We may as well take this mini project through to its conclusion right? After painting the walls and fitting the skirting, I attached the brackets. I can't use the fixings provided as the wall is insulated plasterboard so instead I used long hammer fixings to get through to the brick and used 4 fixings per bracket rather than 2.

I then lifted the radiator on and wrapped PTFE tape over the thread that goes into the radiator on both sides, as well as for the bleed valve and blank cap at the top.

Compression fittings shouldn't have PTFE tape on them. The olive does the work. Just tighten it, a lot.

After that I opened the TRV, lockshield and bleed valve and let the rad fill from the filling loop. I then closed the bleed valve and waited by the filling loop until the pressure was between 1 and 2 and turned that off. Job done.

Here it is after carpeting. I added white plastic pipe covers and on the left using Snappit pipe sleeves. They're quite chunky compared with the usual pipe sleeves. To compare, the pipe on the right here is just the bare speedfit pipe with the writing turned towards the wall which looks okay too.

I've not had to balance our radiators, they all seem to heat up quickly but if I find I need to and don't want the kiddo meddling with it afterward, the valves did come with a spare fixed cap for the lockshield so that it can't be turned.

Radiator foil?

I've read mixed things about whether it's worth sticking radiator foil to your wall behind a radiator. Some think it's effective and others not at all. Without bothering to drill down into the numbers my guess is if you your rad is against a solid brick or block wall that sucks a lot of heat, foil may be worth it to radiate heat back towards the room (it's cheap and easy enough after all). For my wall which has 40mm of PIR insulation behind the plasterboard, I can't see the point. Thoughts?

👂 Sound Insulation & Floorboards

Going back again to pre-plastering stage I had noticed a few woodworm holes in one joist. There was no frass (sawdust) so I think I can assume this is old but I decided to give it a soaking of wood treatment just in case.

After that I installed acoustic insulation in the joists, same as I did in the bathroom. A full fill of 100 + 70mm. I think it's worth it overall but I should point out the kind of sound it prevents: airborne. So talking, music etc, acoustic wool absorbs a lot of that. A benefit when the boy is sleeping. Anything that vibrates the fabric of the house will still get through - scraping a chair over a hard floor, dropping something or bass music. For that you need decoupling like how I did on the other bedroom's party wall which has worked exceedingly well (features mass and damping elements too).

Finally, I relayed the floorboards. A lesson from the office floor project is not to put them back and fix them in place one by one because you can end up with big gaps towards the end. Or possibly if you've laid them too loosely your last board won't fit. Instead put them all back and remove only the board in front of the one you're fixing so you can see where the joists are.

I used the same fixings as for the chipboard in the bathroom. High quality torx head, two per board per joist. I walked about all around afterward to ensure there was no squeaking. None. Infinitely better than the nails I took out.

Why not chipboard? Well it is good, and very firm, especially if you use D4 adhesive as I did in the bathroom. Even under carpet you can feel the difference which I can attest to as my buddy Steve invited me round to jump up and down on his bedroom floor (perfectly normal in our friendship). Half was chipboard, half wooden planks and the chipboard just feels really solid, but not in an unpleasant way. The reasons I didn't use it here are 1) cost 2) the existing boards are 22mm and 'old growth' (nice tight rings), not the stuff you get today and 3) I like the access which is also one reason why I like carpet upstairs. Just peel it back, lift the underlay, unscrew and lift the boards. Now I can thread ethernet cables, fix a leak or whatever and just put everything back. Can't do that so easily with tongue and groove chipboard, especially if glued to the joists, which is one of my complaints about new-build housing. To be clear though, if the whole floor needed replacing I would opt for chipboard over new planks but if it ain't broke don't fix it.

Bring on the plastering.

👋

I was excited to see Virgin Orbit's launch from the UK this week. Shame it wasn't totally successful but no doubt they'll give it another go. I watched it go up from the bedroom window:

Hit "reply" if you've got any comments on this week's newsletter – otherwise I'll see you next time. Have an epic week :)

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