Hi All.

I'd appreciate some of your thoughts on planning bedroom layouts. Are there any general rules of thumb for bedrooms design? I need to do 3 bedrooms for the kids (expected to last from age 7 to, say, 22 if needed) and one bedroom for me & Mrs.

In my mind the kids' bedrooms need to have:

• Single bed with storage underneath the mattress, with a view of potentially installing a 1.5-sized bed in the future.

• Desk with pedestal and office chair

• Wardrobe

• Bookcase

• Large radiator

• Optional shelving or extra storage, space permitting.

To me, the main decision that needs to be made here is the rad position - everything else can be moved around later.

Rad-wise I'm inclined to install tall double rads on the walls in front of the door openings - otherwise that feels like wasted space as I can't put anything else there. This would be a departure from the more traditional traditional rad-under-window designs though.

Any advice on selecting the right rad type & size is particularly welcome - I'd like to run lower boiler temps if possible, maybe even with a view of switching to a heat pump in the future.

Wardrobe-wise, I want to position them against internal walls to avoid mould issues that I've raised in another thread.

Desk to be positioned next to a window (but not directly facing it, as that would make it hard to look at a pc screen).

This is pretty much where my thinking ends. Is there anything else to guide the design process?

Here's an example sketch: a type22 rad under the window (current state pic on the left) gets re-plumbed to go in front of the door into the room (pic on the right). Bed either ends up in the corner made up from the external walls (pictured), or is placed away from the west wall, into the middle of the room, at the expense of available open floor area. Mrs' argument is that open floor space is better, as younger kids can spread out their toys there, while older kids might want to use that space for yoga/pushups/situps, musical instruments practice, whatever else they decide to do. My concern is that it might be a cold corner to sleep in.

Cavity wall yet to be investigated, but I suspect either an empty cavity or old UFFI insulation inside.

Another thing to consider: is it an acceptable practice to place two rads opposite each other on the same internal wall (single leaf brick construction)? The home office in the sketch currently has an under-the-window rad that will need to be re-positioned if I'm re-plumbing the bedroom one, so I'm thinking of hanging another tall rad in the office, on the same wall but right opposite as the one in the bedroom.

Thank you.

Edited 19 hours ago19 hr by tetris

A few thoughts from doing similar rooms.

Rad position: a tall double beside or opposite the door is fine these days as long as the windows are decent double glazing. The old reason for putting rads under windows was to counter cold downdraughts off single glazing. If you're keeping older or draughty windows, the under window spot still earns its keep.

Sizing for lower flow temps: work out each room's heat loss first (room by room, there are free spreadsheets about), then size the rad at the flow temperature you intend to run, not the headline catalogue figure. Catalogue outputs are usually quoted at delta T 50, and at heat pump type temperatures you'll get somewhere around 40 to 50% of that, so expect rads roughly twice the size you'd fit for a hot boiler. Type 22 or type 33 gets you there without a huge footprint.

Cold corner: get the cavity looked at before you settle the layout. A borescope through a drilled mortar joint will tell you whether it's empty or has old UFFI in it. Sorting the wall will do more for the cold corner and the mould risk than any furniture shuffle, and it changes your heat loss numbers anyway.

Two rads back to back on a single leaf brick wall is fine. Fix into the brick rather than the mortar joints, and sleeve the pipes where they pass through.

While the walls are open I'd also add sockets either side of the bed position and by the desk.

For as much as you are planning for this house to last until your kids are grown, also consider that life can throw changes at you that means you move early. On that basis design the rooms with the idea of potentially swapping the bed for a full double (with access both sides) assuming the room is big enough. What I mean by this is think about what effect that would have on the room and placement of other things and ensure that the electrics + heating side of things still works if you were to do that. It's not a huge thing but likely doesn't require that much thought but could make marketing the property easier in future if a need to sell arose.

Other than that, I've read on this forum that vertical radiators are not great, especially in low temperature systems. You need to make sure they are plumbed correctly to function and even then you might get less out of them than you expect. Not saying don't do it, just make sure you understand the limitations. In the picture you showed, it looks like a normal type 22 could easily fit in the same space as the tall radiator (though I'm guessing its drawn way too wide). If the space isn't otherwise used on that wall then a lower radiator would allow wall space for art/photos/posters that might be appreciated by youngsters.

Thank you very much, both.

As far as future property appeal, the current plumbing for under-the-window rads just runs down from the ceiling & along the wall, out there in the open. The black dot on top of the bedroom wardrobe in the left pic shows where the pipes go down the wall (inside the old wardrobe). Re-positioning the rads means I get rid of the godawful plumbing and put the new pipes through the built-in wardrobe in the home office. Nicely concealed & no chasing required.

Windows in this room are decent condition double glazed UPVC. The classic rad position suddenly makes sense though - thank you. I like understanding why people do/did things in a particular way.

Re walls, how bad is having old UFFI and is it fine to leave in place for now/forever if it's not actively causing problems? I expect to be very cash-short for the next 6 months, which is a crap position to be in when you just moved into a fixer-upper, but we are where we are due to unfavourable factors outwith our control. I do need to redecorate a couple bedrooms asap though so can't wait a year before I have the funds and the time to deal with wall cavities. I know, it's a bit of a backwards situation, but such is cest la vie.

Now rads are starting to really annoy me, the more I read about them (please bear with me).

We've got building regulations that require us to have condensing boilers because they run more efficiently at < 55C flow return.

That implies rad temp of about 60C when the heating is on.

But most rads are advertised with BTU at T50 or T60, implying rad temp of about 70-80C.

Furthermore, assuming T35, means we need rads rated for about twice as many BTUs, don't we? But there's bugger all supply of high-output rads out there while the market is saturated with rads designed to run at 85C, almost 20 years after we all got switched to condensing boilers. Unless I'm missing something.

How does this fit into the government's plan to hook everyone onto heat pumps at T30?

Doing some eyeballing with AI and heatpunk, for a room that's 3.8mx3.2m and 2.4m tall, assuming indoors temp of 18C and outdoors of 0C, I need about 1000-1200W from the rads, which is about 4k BTU at T30, so 8k at T50. This places me into 1800x600cm-sized tall rads, doesn't it?

For a type 22 it would have to be almost 1.5m wide, which may be OK as plan B, but is a bit too tight space-wise for my liking.

Still possible to find tall rads in this size for a couple hundred £, but is my ballpark calc correct?

Thank you.

You were right - I've drawn the tall rad way too wide. Adjusted to 600cm for the visual.

Double bed just about fits as does a 1.5m-wide Type 22.

11 minutes ago, tetris said:

Thank you very much, both.

As far as future property appeal, the current plumbing for under-the-window rads just runs down from the ceiling & along the wall, out there in the open. The black dot on top of the bedroom wardrobe in the left pic shows where the pipes go down the wall (inside the old wardrobe). Re-positioning the rads means I get rid of the godawful plumbing and put the new pipes through the built-in wardrobe in the home office. Nicely concealed & no chasing required.

Windows in this room are decent condition double glazed UPVC. The classic rad position suddenly makes sense though - thank you. I like understanding why people do/did things in a particular way.

Re walls, how bad is having old UFFI and is it fine to leave in place for now/forever if it's not actively causing problems? I expect to be very cash-short for the next 6 months, which is a crap position to be in when you just moved into a fixer-upper, but we are where we are due to unfavourable factors outwith our control. I do need to redecorate a couple bedrooms asap though so can't wait a year before I have the funds and the time to deal with wall cavities. I know, it's a bit of a backwards situation, but such is cest la vie.

Now rads are starting to really annoy me, the more I read about them (please bear with me).

We've got building regulations that require us to have condensing boilers because they run more efficiently at < 55C flow return.

That implies rad temp of about 60C when the heating is on.

But most rads are advertised with BTU at T50 or T60, implying rad temp of about 70-80C.

Furthermore, assuming T35, means we need rads rated for about twice as many BTUs, don't we? But there's bugger all supply of high-output rads out there while the market is saturated with rads designed to run at 85C, almost 20 years after we all got switched to condensing boilers. Unless I'm missing something.

How does this fit into the government's plan to hook everyone onto heat pumps at T30?

Doing some eyeballing with AI and heatpunk, for a room that's 3.8mx3.2m and 2.4m tall, assuming indoors temp of 18C and outdoors of 0C, I need about 1000-1200W from the rads, which is about 4k BTU at T30, so 8k at T50. This places me into 1800x600cm-sized tall rads, doesn't it?

For a type 22 it would have to be almost 1.5m wide, which may be OK as plan B, but is a bit too tight space-wise for my liking.

Still possible to find tall rads in this size for a couple hundred £, but is my ballpark calc correct?

Thank you.

On the UFFI, after this many years it has long since finished giving off formaldehyde, so it isn't a health worry left in place. The usual problem is that it shrinks and cracks, which can leave cold patches and occasionally lets driving rain track across to the inner leaf. If you've no damp patches or mould on the inside of the exposed walls, I'd just redecorate and leave it. Keep the pointing, gutters and sills in decent order and look at extraction or a top up later when funds allow.

Your sums are about right. A room that size needing 1000 to 1200W is plausible with older walls, and at a mean water temperature of around 50C (so delta T 30) a rad gives roughly half its delta T 50 catalogue figure. So you're looking at 2000 to 2400W at delta T 50, which is about what a 600 high by 1400 to 1500 wide type 22 does, or a shorter type 33 if width is tight. Check the manufacturer's correction factor table rather than relying on the rule of thumb. Insulating the walls later will bring the number down a fair bit.

Thank you. But I take it sizing the rads for more output, as long as the space allows, is not a problem, is it? A TRV should moderate the heat output and I'll have a bit of extra oomph for the extra cold winters?

18 minutes ago, tetris said:

Thank you. But I take it sizing the rads for more output, as long as the space allows, is not a problem, is it? A TRV should moderate the heat output and I'll have a bit of extra oomph for the extra cold winters?

Sorry below maybe an old response written while I was in the woods walking the dog with nut much signal.

You maybe thinking of sizing radiators a little wrong. You are not oversizing for more output, more to allow a low flow temperature from the boiler. Lower flow temp from boiler allows much higher efficiency and less gas usage and same room temperature.

But to take advantage you need to follow the same approach with all rooms and not be a system or heat only boiler on S or Y plan.

What is your scope of work for the whole house?

Edited 2 hours ago2 hr by JohnMo
Delay in sending missed recent posts

Just to reinforce what John said. Even T30 is high if you are trying to get most efficiency. Both heatpumps and boilers will be most efficient if sized correctly and ran at a water temp <40C. That's T15-T20.

That might not be possible in an old property without more major works than you are planning but is something to bear in mind as you plan changes. If you want to dive into what savings can be made here look at:

It's a big long thread and I suspect too much to worry about doing right now. But @marshian at various points shows the gains/cost savings made by his changes and might give you an end goal to aim for in a few years and allow you to avoid doing some things twice.

17 minutes ago, -rick- said:

Both heatpumps and boilers will be most efficient if sized correctly

It's a big long thread and I suspect too much to worry about doing right now. But @marshian at various points shows the gains/cost savings made by his changes and might give you an end goal to aim for in a few years and allow you to avoid doing some things twice.

Oh I've made a lot of mistakes over the course of my journey!!!

My key points

Size the boiler for the house/hw recharge

Size all the rads for the output required for the flow temp and room heat loss

Get a decent HW tank with a 2.3 to 3.0 m2 coil surface area so you can heat water and still have the boiler in condensing mod

Use WC and control the flow temp rather than bouncing room temps of TRV limits

1 hour ago, JohnMo said:

You maybe thinking of sizing radiators a little wrong. You are not oversizing for more output, more to allow a low flow temperature from the boiler. Lower flow temp from boiler allows much higher efficiency and less gas usage and same room temperature.

Yep. What I meant is that if I oversize the rads and size for lowest flow temp (or size them for more heat loss than I end up with) there's no negative impact apart form rads taking up more space & being marginally more expensive?

And when we get a few cold weeks of -5C in winter, I can just up the boiler temp for the cold period.

1 hour ago, JohnMo said:

What is your scope of work for the whole house?

Ask me again next time I lift a floorboard 🫣.

The scope changes as we're discovering more about the house and I'm reading up more about efficiency, ventilation, etc. We bought it as a fixer upper and that was reflected in the price, but on moving in, we keep discovering new challenges every week. And we had some challenges thrown at us with selling our old property, so had to change our plans to battening down the hatches and surviving this winter before doing anything major to the new house.

Overall, the plan is to incrementally retrofit with minimum alteration to existing fabric unless necessary and maximum energy efficiency per hour of work (which will be mainly done by yours truly). We're definitely sorting out all of the windows before the end of the year so should have fully working pvc double glazing everywhere.

In spring/summer I'll be insulating sections of the house where we have suspended wooden flooring.

I'll be doing a fair bit of re-plumbing and replacing the rads, but do it incrementally as I move on to each room. Not sure if it's worth switching to a home-run manifold in the end.

I need to sort out ventilation. Plan is to go for dMEV, but that's probably a topic for another thread.

The bit that's got me checkmated is the suspended concrete floor in two bedrooms, home office corridor & potentially, one bathroom & kitchen. It seems to be uninsulated, but if I understand correctly, adding insulation on top of it is the only option apart from pouring a solid slab, and it means raising door openings, which suddenly becomes a very big job. Ceilings are 2.4m however, so there's space for it.

In terms of heating & insulation, we've got an old combi boiler with no water tank, that must be on its last legs and I expect will need to be replaced in the next 2 years. Maybe sooner.

Thermal imaging shows that, once I sort out the windows, by far the biggest heat loss is coming from floor voids in rooms with uninsulated suspended wooden flooring.

Current rad arrangement is pants and needs to be revised.

I'm looking into A2A heat pumps for the living room and, potentially, the far bedroom with 3 external walls and large areas with windows & French doors.

Edited 22 minutes ago22 min by tetris

Combi boiler already gives you room to have CH and DHW at very different temps. If you are adding more insulation your existing rads may be fine or something you sort out later when funds allow. If you replace the boiler get one that allow you run weather compensation (WC). Then with correct sizing you run most the time in the low 30 for CH, cold snap the flow temp will naturally increase to compensate.

The idea is you run long and low, you warm the building fabric and that also allows the house to feel warmer at a lower room temp , that also which lowers heat loss. Once return temp drops below 53 degs you are in condensing mode, the further you fall below the more condensation and the more efficient your boiler.