Old radiators - hot to touch but room cold

[b21playa]

Hi all

Moved into a new (new to me) house a few weeks ago which has an old heating system; gravity hw and pumped heating. Just changed this to fully pumped as had no control over hw.

Now the problem is the radiators are hot to touch but the rooms don’t really heat up. There are double radiators in majority of the rooms and some have 2-3. There are no convector fins on these and look like they’ve been painted over the years.

Starting to get colder and need to try and sort this out. Would changing the radiators help with heat transfer?

Many thanks

 

[oz-plumber]

Touch the piping connecting each end of the radiator.
There should be a hot pipe and the other pipe should be almost as hot.
If there is a noticeable difference then there is a flow problem.

If the pipes are roughly the same temperature then the radiator is not big enough

 

[Gasmk1]

how long do you have the heating on for

 

[b21playa]

Touch the piping connecting each end of the radiator.
There should be a hot pipe and the other pipe should be almost as hot.
If there is a noticeable difference then there is a flow problem.

If the pipes are roughly the same temperature then the radiator is not big enough

There is a slight difference in temp on the pipes, so I can tell which is flow & return

 

[b21playa]

how long do you have the heating on for

Used to be a few hours in morning, then few hours in the evening but now got it on constantly which has taken the chill out the rooms but never gets to 20deg

 

[fronty]

Have checked they are all balanced correctly? I have some older style rads in my home (no fins), and while they are probably not as good as modern radiators they still pump out a lot of heat.

 

[Gasmk1]

Used to be a few hours in morning, then few hours in the evening but now got it on constantly which has taken the chill out the rooms but never gets to 20deg

ok only asked because a lot of people expect the house to warm up in a couple of hours in the moring then 3 or 4 in the evening

 

[Knappers]

Are the rads hot all over?
Sludge can block the center and you get heat only round the edges.
How long do they take to heat up?
System should heat the house (from a reasonable starting point) In around an hour (or so)

 

[b21playa]

Have checked they are all balanced correctly? I have some older style rads in my home (no fins), and while they are probably not as good as modern radiators they still pump out a lot of heat.

Most valves are stuck, very old system

 

[b21playa]

Are the rads hot all over?
Sludge can block the center and you get heat only round the edges.
How long do they take to heat up?
System should heat the house (from a reasonable starting point) In around an hour (or so)

Yes hot all over now, they weren’t but put some cleaner in and attached my magnacleanse to the system and used the vibra attachment to loosen sludge

I’ve ordered a few rads to replace one room as see how it goes. One is hanging off the wall so needs sorting along with a drain valve as it’s at the lowest point and no way of draining

 

[Knappers]

Make sure you flush out that cleaner!

 

[b21playa]

Will do, been in there a week, will be drained this weekend when I fit rads and add the drain point, which should help drain it out and help with future draining as I slowly change/add radiators

 

[fronty]

Will do, been in there a week, will be drained this weekend when I fit rads and add the drain point, which should help drain it out and help with future draining as I slowly change/add radiators

It sounds like you are doing what I did when I moved into my house, I called it the "Radiator Replacement Programme" lol. I've replaced 10 old style (no fins) rads now but still have a couple left.

I actually have a bit of a dilemma because both of these remaining old rads are in the living room where the room stat is, so neither of them have TRVs, and if I replace them with newer ones I suspect what will happen is the living room will get up to temp a lot quicker, causing the the boiler to shut down prematurely before the rest of the house has got up to temp. So I'm leaving them as they are for now until I can figure out the best approach.

 

[b21playa]

Haha, does sound similar

I’ve just fitted my hive, so can move the thermostat luckily. I’m planning on changing the rads in rooms we regularly use, and the rest will be done when I extend/refurb the house

 

[Knappers]

Good luck!

 

[Rob Foster]

If the rads are working ok , is the boiler modulating ? Turning itself on and off or blasting away ? You might have too small a boiler and or too small low output rads for your Gaff ..report back Rob Foster
Aka centralheatking

 

[ShaunCorbs]

If rads are hot my guess is there not sized correctly

 

[Gasinspect]

check floor insulation, wall insulation, double glazing, roof insulation - if radiators are hot and room cold, you have a heat loss problem. had one customer who had removed underlay and carpets during the summer, and sanded their old floorboards, then wondered why cold in winter. laid a newspaper on the floor and it fluttered in the draught between the old boards. Treat yourself to a Black and Decker Thermal Leak Detector, about £30, real eye-opener, cheaper than Thermal Imaging Camera but useful tool.

 

[Ric2013]

An old system may not even be designed to give you 20°C in every room. And it may be designed to give design room temperatures when outside is -1°C or more and it could be that it is colder wherever you are? But to get full output, the boiler needs to be set to its highest temperature. I assume your old boiler has a manual control knob on it probably labelled 1 to 6 or something like that? What number is it currently on?