Adding an extra radiator to the main flow to the manifold

[MikeGrahamT21]

I have one area which is quite large in total, covered by a fairly big double vertical radiator, i was hoping once i'd finished and everything was fully insulated and sealed up, it would be up the job of heating the whole space, but I think the kitchen lets it down (furthest away from the rad), which is dot and dab (which i've tried to foam behind, but still get air leakage, probably due to thermalite blocks shrinking), and poorly fitting spot lights (which is on my to-do list), with 4 double glazed circa 2011 velux windows.

 

Heating graph shows a fairly normal, dark winters day:

 

When its sunny the thermal gain is good enough to help heat the room quickly:

 

I've no more ports available on the manifold, and the days of taking the floor up to feed pipes through is now gone, however I've had a thought, and wanted to know whether it was feasible...

 

So the boiler is on the wall right next to where the kitchen is, and i'd wondered about drilling two holes through the wall and tapping into the 22mm flow feed (which goes to the manifold), and making it another bypass radiator to go with bathroom (though this goes via manifold). Had a look and found some 22mm valves, with a 3/4" inlet fitting, but radiators with this seem few and far between, will keep looking.

 

Boiler Flow Pipe > Small Rad > Flow Pipe to Manifold > to rest of rads > and then Return back to boiler

 

Another idea, which would give out much less heat, would be to make a radiator from 22mm copper pipe.

 

What I want to know is basically is this feasible? I'm thinking it could impact flow rates to the manifold hence why i've gone looking for large bore fittings? Any one ever done anything like this before?

 

Radiator sizing would have an output of between 1000 and 2000 BTU, just pinching a small amount of energy on its way to the rest of the bungalow.

 

Just to add current flow temp is set at a max of 46C, but my Tado optimises this based upon the weather, and it generally sits around 42/43C. Of course this could be turned up which would help, but i'm trying to future proof in case I have to have an ASHP at some point.

 

Thoughts?

 

Cheers

Mike

Edited January 28 by MikeGrahamT21

[JohnMo]

What is the target room temperature? How many thermostats are in the house?

 

Run less setback overnight and during the day, then the radiator and boiler has less work to do next morning. Try running the same temperature 24/7 does that fix the issue? You may find the boiler in general has less work to do so operation is at a lower max temperature and uses less gas.

[MrPotts]

Vertical radiators are notoriously poor at space heating, maybe swapping the radiator for a conventional convecting radiator might heat the space better. Have you calculated the heat loss of the room?

[JohnMo]

46 minutes ago, MrPotts said:

maybe swapping the radiator for a conventional convecting radiator

Or even fan assist radiator?

[MikeGrahamT21]

49 minutes ago, JohnMo said:

What is the target room temperature? How many thermostats are in the house?

 

Run less setback overnight and during the day, then the radiator and boiler has less work to do next morning. Try running the same temperature 24/7 does that fix the issue? You may find the boiler in general has less work to do so operation is at a lower max temperature and uses less gas.

 

Target temp is 18.7C which I find more than warm enough, today is another miserable day but milder, and already above this target.

 

Overnight i've had it set to Off for some years now, which works in most cases, its just the cold cold days where it struggles a bit. This year, from 1st to 28th (so far), this room has consumed 347.51 kWh in gas according to the Tado calculation. I'll have a mess with overnight temps rather than it being off completely, and see how it compares.

 

There are 4 controlled zones, Dining room (this one which also includes snug and kitchen), Bedroom 1, Living Room and Garden Room (includes Bedroom 2). Other zones are Utility and Bathroom which just act as bypass radiators taking whatever heat they can whilst the system is on.

 

24 minutes ago, MrPotts said:

Vertical radiators are notoriously poor at space heating, maybe swapping the radiator for a conventional convecting radiator might heat the space better. Have you calculated the heat loss of the room?

I hadn't heard they were poor, they were amongst the highest in heat output when i was looking at new rads for a given size. Wouldn't be able to swap for anything else really as don't want to mess with flooring and break airtightness, so restricted with width. There is the possibility of getting a triple version of the vertical, currently have double.

 

 

 

This was the calculation I did a while ago, but the flow temperature has been reduced 10C compared to 55C which i was originally aiming for.

 

Having lived in it, i don't think it needs a huge amount more output, which is why I was wondering if a small radiator branched off of the flow run would work, and not compromise flow to the rest of the system? And this is more future planning than anything else.

[MikeGrahamT21]

Went through this spreadsheet, as i'd got some incorrect values in there, and also changed the room temperatures to what i like them at

 

 

Any further thoughts on my original idea as to whether it would be feasible to do this with the flow circuit to manifold?

[MikeGrahamT21]

Have also just discovered that the flow diverters aren't always included as standard, will attempt to use the thermal camera to see if i can see any signs of one in them. The radiators do get evenly hot, but take some time to heat all of the bars, maybe this is part of the issue?

[marshian]

On 31/01/2025 at 12:41, MikeGrahamT21 said:

Have also just discovered that the flow diverters aren't always included as standard, will attempt to use the thermal camera to see if i can see any signs of one in them. The radiators do get evenly hot, but take some time to heat all of the bars, maybe this is part of the issue?

 

I'm not sure if it helps but I put vertical rads in two bath rooms (the towel rail ladder type rads just weren't cutting it) They were heating the rooms fine at higher flow temps (~55 plus) but one was bloody awful at lower flow temps {~40 deg C)

 

They were both had equally poor delta T between the flow and return at either higher flow temps or lower flow temps but one definately wasn't much of an improvement on the old ladder type towel rail.

 

I took the worst one off the wall removed the lockshield and trv and shone a torch down it whilst taking a picture from the other end

 

 

That light you can see is the clearance around the inbuilt diverter

 

I knocked it out and fitted one of these (trimmed it to size)

 

 

Difference was like night and day you could feel the first 3 columns getting warm the flow rising to the top and the the cooler water leaving the rad down the columns on the other side.

 

It was so effective I did the same to the other identical rad - and that one was better too and now they heat the bathrooms to 22 deg C fine even at ~30 deg flow temp

 

 

[MikeGrahamT21]

10 hours ago, marshian said:

 

I'm not sure if it helps but I put vertical rads in two bath rooms (the towel rail ladder type rads just weren't cutting it) They were heating the rooms fine at higher flow temps (~55 plus) but one was bloody awful at lower flow temps {~40 deg C)

 

They were both had equally poor delta T between the flow and return at either higher flow temps or lower flow temps but one definately wasn't much of an improvement on the old ladder type towel rail.

 

I took the worst one off the wall removed the lockshield and trv and shone a torch down it whilst taking a picture from the other end

 

 

That light you can see is the clearance around the inbuilt diverter

 

I knocked it out and fitted one of these (trimmed it to size)

 

 

Difference was like night and day you could feel the first 3 columns getting warm the flow rising to the top and the the cooler water leaving the rad down the columns on the other side.

 

It was so effective I did the same to the other identical rad - and that one was better too and now they heat the bathrooms to 22 deg C fine even at ~30 deg flow temp

 

 

Wow, yeah just a slight gap! lol

 

Had a look other day with the Thermal Image camera, and could see a point on the bottom bar around half way where the temperature differed on each side, so I'm guessing there must be a flow restrictor in there. The big ones of these are 8 bars wide, the first 4 bars were slightly hotter than the second 4 bars, which married up with the point where it seems there is a flow restrictor, so it seems in my case this may not be the issue, and the whole of the rad generally showed quite evenly hot.

 

If they ever come off for any reason, i'll be sure to check this, very useful thank you

[marshian]

1 hour ago, MikeGrahamT21 said:

Wow, yeah just a slight gap! lol

 

I was a bit surprised at what I saw - quality control clearly not the best

 

1 hour ago, MikeGrahamT21 said:

Had a look other day with the Thermal Image camera, and could see a point on the bottom bar around half way where the temperature differed on each side, so I'm guessing there must be a flow restrictor in there. The big ones of these are 8 bars wide, the first 4 bars were slightly hotter than the second 4 bars, which married up with the point where it seems there is a flow restrictor, so it seems in my case this may not be the issue, and the whole of the rad generally showed quite evenly hot.

 

Sounds like they are functioning relatively well - verticals really do seem to need a bit more flow and a slightly higher flow temp than an equivalent T11 or T22 to get the same heat output

 

1 hour ago, MikeGrahamT21 said:

If they ever come off for any reason, i'll be sure to check this, very useful thank you

 

Worth a look - I have a very large vertical (Millano) with a built in diverter and after my experiences above I had a good look in that one and it's 100% diverted

 

[MikeGrahamT21]

Rather than totally diverting the flow entirely through another radiator, would it be instead feasible to use 2x reducing tees on the main flow pipe out of the boiler, keeping the 22mm straight through, with 2x 15mm pipes going to and from an additional radiator?

 

I've had a look at heating pipe designs, and think this small section would fall into a 1 pipe heating system with bypass, with the remainder being a 2 pipe? Would it just mean a slightly prolonged heating period for the additional radiator on the 1 pipe?

 

Alternative to keep a two pipe would be a total diversion through the radiator before manifold, but then going through a 1/2 valve (which would be permenantly open) would this lead to too much pressure loss?

 

I'm thinking using the 1 pipe with bypass may be an ideal neat solution for a little extra heat in the one room which is struggling?

[marshian]

On 03/02/2025 at 21:47, marshian said:

 

I'm not sure if it helps but I put vertical rads in two bath rooms (the towel rail ladder type rads just weren't cutting it) They were heating the rooms fine at higher flow temps (~55 plus) but one was bloody awful at lower flow temps {~40 deg C)

 

They were both had equally poor delta T between the flow and return at either higher flow temps or lower flow temps but one definately wasn't much of an improvement on the old ladder type towel rail.

 

I took the worst one off the wall removed the lockshield and trv and shone a torch down it whilst taking a picture from the other end

 

 

That light you can see is the clearance around the inbuilt diverter

 

I knocked it out and fitted one of these (trimmed it to size)

 

 

Difference was like night and day you could feel the first 3 columns getting warm the flow rising to the top and the the cooler water leaving the rad down the columns on the other side.

 

It was so effective I did the same to the other identical rad - and that one was better too and now they heat the bathrooms to 22 deg C fine even at ~30 deg flow temp

 

Just because of continuity (and a bump for a question unanswered)

 

The diverter only actually stops the flow past the first two columns

 

Here's the rad in situ

 

 

And here's the thermal image

 

[MikeGrahamT21]

10 hours ago, marshian said:

 

Just because of continuity (and a bump for a question unanswered)

 

The diverter only actually stops the flow past the first two columns

 

Here's the rad in situ

 

 

And here's the thermal image

 

I too got the thermal camera out on my verticals and could clearly see the diverter. In my case it was half and half, diverter was clearly visible in the centre of the bottom horizontal 

[marshian]

12 minutes ago, MikeGrahamT21 said:

I too got the thermal camera out on my verticals and could clearly see the diverter. In my case it was half and half, diverter was clearly visible in the centre of the bottom horizontal 

good tool - I should have borrowed this one sooner

[marshian]

On 13/02/2025 at 12:57, MikeGrahamT21 said:

Rather than totally diverting the flow entirely through another radiator, would it be instead feasible to use 2x reducing tees on the main flow pipe out of the boiler, keeping the 22mm straight through, with 2x 15mm pipes going to and from an additional radiator?

 

I've had a look at heating pipe designs, and think this small section would fall into a 1 pipe heating system with bypass, with the remainder being a 2 pipe? Would it just mean a slightly prolonged heating period for the additional radiator on the 1 pipe?

 

Alternative to keep a two pipe would be a total diversion through the radiator before manifold, but then going through a 1/2 valve (which would be permenantly open) would this lead to too much pressure loss?

 

I'm thinking using the 1 pipe with bypass may be an ideal neat solution for a little extra heat in the one room which is struggling?

 

Anyway the bump was to hopefully help get an answer to your question @MikeGrahamT21 - I don't have a clue on what the impacts would be