Radiator Advice

[Time Waster]

Just bled our radiators. Bathroom towel rail radiator was always cold. Did the whole house then turned the heating on to way above the temperature setting we normally have it at. Thought I'd give it some because the towel radiator didn't initially heat up like the others. Now it's hot so that's one issue sorted.

My other issue is that the radiators are old. My last house I put the central heating in with a high efficiency boiler and high efficiency radiators. I believe several As in efficiency ratings. That system heated a solid stone walled, poorly insulated, mid terrace house in less than 10 minutes. Basically away without heating on for a week with a very cold house, it heated in 10 minutes. This house doesn't, it takes over half an hour despite being a more modern house that's well insulated for a 70s house. Loads of loft insulation, cavity insulation, bungalow over a garage/undercroft with insulation there too.

The existing radiators get hot quick enough just isn't sending the heat out as efficiently I think. They get the house hot and we turn the heating right down and the radiators hold heat longer. They're not the classic cast iron looking ones but 70s style heavy ones with one or two panels and no metal fins. We're wondering if it's worth looking at replacing the radiators? Are modern ones noticeably better? Could we swap wide radiators that are not very high with smaller ones?

Anyone got recommendations?

 

[Profpointy]

A radiator with more surface area will give out more heat - be that having fins, extra layers or simply bigger. It's probably worth noting that it won't strictly be "more efficient" as you will be using more gas for it to be able to warm your house faster. Given they are all made of thin mild steel of much the same thickness a "modern" one isn't per se better unless it was more surface area.

 

[sleuthey]

What you need is double panel double convector radiators. In a way you have answered your own question - you state the rads hold the heat - if they were efficient they would not as the heat would have RADIATed into the room.

 

[sleuthey]

 

[Fastpedaller]

Folk seem to always bleed radiators as a first go-to! Maybe because it's easy, or they know what to do? I'm unsure, but it rarely provides a 'cure'.
First I'd ask....... Is the rad hot at the bottom but not the top? If so it may need bleeding If that isn't the case it may be the 'balancing' of the radiators..... Each radiator has a 'lock-shield' valve at one end and either a manual adjustable or thermostatic valve at its other end. Without access to any thermometers, the easiest way of setting all the radiators (balancing the system) is to start by reducing the heat of the hottest radiators (especially if they are too hot to touch). This is achieved by removing the cap on the loch-shield valve (either just pull off, or undo a small screw and pull off) and turning it clockwise with an adjustable spanner to diminish the flow -it may only be a small amount (maybe 1/4 turn) and is rarely more than 1 full turn. Leave it all to settle several minutes. Similarly if radiators are cold, increase the floe to those ones by turning the lockshield a little anti-clockwise. It can take several hours to get the balance right. To 'summarise' the hottest ones can 'rob' the cold ones of heat, hence the problem. Has the system ever been cleaned, either by professional equipment (expensive) or back-flushing and corrosion inhibitor added? If not, the result can be a rusty sludge in the radiators which sometimes causes terminal damage(rusted heat exchanger on boiler, and rusted radiators) and cuts efficiency drastically.

 

[Time Waster]

The bleeding worked well on the bathroom towel rail radiator at evidenced by cold all the time became hot after doing it. There was a hiss then the water spouted out in a jet from the top of one side where the bleed valve is. I tried bleeding all the others but they mostly spouted water. One or two kind of slow dribble then a bit more flow. Then I increased the boiler water n pressure to fractionally over 1 bar. Then heating on and then everything seemed to be a bit better. The bathroom was warm for the first time since we stopped using the heating in the spring.

Our old house jab radiators with those zigzag metal fins between radiator panels. I also thought the material they're made of was thinner than the older ones in this house. I've also read that less material I the panels and less water needed can improve heating system efficiency. Smaller internal spaces in radiators mean less water and less water to heat up. However more efficient heat transfer from radiator to room can mean this is possible. Or something like that. You're heating the room not heating a ticket mass of radiator.

Whatever the case the point of radiators is to take heat from warm n water and convect it into the air of the room. Surface area and creating the flow around the radiator and through it. Fins, I'd have thought, help with transfer of water and radiator heat to air between two panels. Single panels don't have fins so I guess there's a reason for that top.

 

[raleighnut]

The bleeding worked well on the bathroom towel rail radiator at evidenced by cold all the time became hot after doing it. There was a hiss then the water spouted out in a jet from the top of one side where the bleed valve is. I tried bleeding all the others but they mostly spouted water. One or two kind of slow dribble then a bit more flow. Then I increased the boiler water n pressure to fractionally over 1 bar. Then heating on and then everything seemed to be a bit better. The bathroom was warm for the first time since we stopped using the heating in the spring.

Our old house jab radiators with those zigzag metal fins between radiator panels. I also thought the material they're made of was thinner than the older ones in this house. I've also read that less material I the panels and less water needed can improve heating system efficiency. Smaller internal spaces in radiators mean less water and less water to heat up. However more efficient heat transfer from radiator to room can mean this is possible. Or something like that. You're heating the room not heating a ticket mass of radiator.

Whatever the case the point of radiators is to take heat from warm n water and convect it into the air of the room. Surface area and creating the flow around the radiator and through it. Fins, I'd have thought, help with transfer of water and radiator heat to air between two panels. Single panels don't have fins so I guess there's a reason for that top.

Modern 'single panel' radiators often have fins attached to the back to increase their heat output.

 

[Hicky]

A possible issue is the fins are full. Unless you clean em out then dust etc can accumulate, if you have pets the hair gets in there. We moved house 3 yrs ago and had a similar issue, cleaned em out and viola, once they’re balanced job jobbed.
Find a btu calculator to check you have the right size for the room.

 

[Time Waster]

Our old house had radiators with the fins but our current house has radiators without fins. If we're in this house for about 5 years I wonder if it's even worth replacing them for modern ones with the fins? I don't think so but don't know for sure.

 

[Profpointy]

What you need is double panel double convector radiators. In a way you have answered your own question - you state the rads hold the heat - if they were efficient they would not as the heat would have RADIATed into the room.

The last part isn't quite right, flat out wrong in fact. Radiators will be maintained at the temperature the boiler is set to heat the water so if a rad is cooler it isn't because it is heating the room better unless the boiler isn't up to the job. The bigger the temperature difference between the rad and the room, the more heat will be transferred

And pedantically, radiators don't radiate (much), they heat by conducting heat to the air, which is then moved round the room by convection. Radiated heat is negligable

 

[wiggydiggy]

Can I piggyback a radiator question here? I have a brand new boiler with an old pipe/radiator system. I don't have spare £ to make any changes to the radiators right now (see earlier comment about new boiler lol!) I'd like to reduce the heat they give out in rooms I'm not in but I'm lacking clear controls on the radiators, I have a valve at one end on each one I can turn to off which will turn it off, but it's not numbered like others I have seen to let me control the heat.

Question is, does only having it open to 1 turn (instead of 6 to open it 'full') reduce the heat they give out, or do they not work like that?

 

[Alex321]

The last part isn't quite right, flat out wrong in fact.

Apart from using the word radiate, it was quite right.

You appear to have missed the fact that they were talking about the radiators holding heat for quite a while after the boiler is turned off. Not about them being hot while the system is running.

 

[Alex321]

Can I piggyback a radiator question here? I have a brand new boiler with an old pipe/radiator system. I don't have spare £ to make any changes to the radiators right now (see earlier comment about new boiler lol!) I'd like to reduce the heat they give out in rooms I'm not in but I'm lacking clear controls on the radiators, I have a valve at one end on each one I can turn to off which will turn it off, but it's not numbered like others I have seen to let me control the heat.

Question is, does only having it open to 1 turn (instead of 6 to open it 'full') reduce the heat they give out, or do they not work like that?

The valves with numbers on are generally thermostatic vales, which only open to let water through at the temperature represented by that number.

If yours don't have those, then having the valve partially open rather than fully will have some effect, but not very much, until they are so close to closed that the radiators will hardly heat up at all.

 

[wiggydiggy]

The valves with numbers on are generally thermostatic vales, which only open to let water through at the temperature represented by that number.

If yours don't have those, then having the valve partially open rather than fully will have some effect, but not very much, until they are so close to closed that the radiators will hardly heat up at all.

I thought thermostatic valves were something else entirely so thanks! What you say was though with mine I'll monitor them tonight at 1 turn and keep going lower till I see a difference.

 

[lazybloke]

Folk seem to always bleed radiators as a first go-to! Maybe because it's easy, or they know what to do? I'm unsure, but it rarely provides a 'cure'.

My towel rail is the highest rad in the system and collects gas - the top gets cool/cold in winter f I don't bleed it a couple of times a year.

As it's a pressurised sealed system I doubt air is being admitted; I suppose there's a galvanic/chemical reaction somewhere.