column radiator problem

[David Stellaman]

Having problems with a designer column radiator that I bought. To cut a story short, it gets hot, all columns are hot to touch, tip, middle and bottom but it doesn't heat the room at all. After about an hour all other rooms are hot but the one with the column rad is cold even though it is hot to touch. The btu rating is 4705 at 60 C. Btu calculations for the room average 3500 so should be plenty. Is there any way of measuring the actual btu output? Do new rads go faulty? Anyone with experience on how to approach the company? Initial enquiries have drawn a blank...


Dave from Siberia

 

[Chalked]

Can you tell us the exact rad, where its fitted in the room and the room dimensions please.

 

[David Stellaman]

Hi. Thanks for the swift reply. Bilbo Anthracite Double Panel designer radiator with Mirror 1800x381. It's fitted to an outside South facing wall. . This is one btu calculation with the dimensions.

Dave

 

[David Stellaman]

This is the exact radiator. Not sure whether 'column' is the correct term for this.

Dave

 

[Radioman]

This is a Common issue with so called designer radiators IMO and experience. If you look at the design of a modern double panel radiator the actual area that radiates heat is 4 times larger than the radiator area. It also has heat dispersal fins to aid radiation. Panel rads are fitted close to the ground so that the area of convection is greater. Black is not a good radiant colour, white is the best.
You may also have some insulation issues in that one room.

It is possible that the BTU rating of that particular rad has been overstated. Another check would be to take the surface temp of the radiator to see if it is getting hot enough, and then maybe try and balance the heating system. Plenty of advice on how to do that on the web.

But my suspicion is you will never get that rad to heat the room.

 

[David Stellaman]

This is a Common issue with so called designer radiators IMO and experience. If you look at the design of a modern double panel radiator the actual area that radiates heat is 4 times larger than the radiator area. It also has heat dispersal fins to aid radiation. Panel rads are fitted close to the ground so that the area of convection is greater. Black is not a good radiant colour, white is the best.
You may also have some insulation issues in that one room.

It is possible that the BTU rating of that particular rad has been overstated. Another check would be to take the surface temp of the radiator to see if it is getting hot enough, and then maybe try and balance the heating system. Plenty of advice on how to do that on the web.

But my suspicion is you will never get that rad to heat the room.

Thanks for the reply Radioman. This seems to be the general consensus regarding designer rads. I am not happy that it is described as offering "exceptional heat output...". Will try balancing the system as you advise and will let you know the outcome.
Thanks for replying, Dave

 

[Last Plumber]

A few quick points.
1st Are you sure you've got the wall type correct ?
2nd Have you checked the delta T on the rad ?
3rd I think your on line heat loss device /calc is wrong. It should be higher

 

[David Stellaman]

Thanks for the reply. Yes, the wall type is correct. Also the area of the room I have overestimated by a quarter due to its shape. I tried four different sites for btu calculations and none came anywhere near the rads btu figure. The Delta T? Don't know what that is but I'll read up on it thanks

Dave

 

[Last Plumber]

Thanks for the reply. Yes, the wall type is correct. Also the area of the room I have overestimated by a quarter due to its shape. I tried four different sites for btu calculations and none came anywhere near the rads btu figure. The Delta T? Don't know what that is but I'll read up on it thanks

Dave

Basically it is the difference between the room temp and surface of rad temp.
Have a look at what the rad manufacturers give as delta T when they give the output. The delta is symbolised with a triangle as you probably know. So it will be a triangle with a number. The number will be temp diff in Centigrade. So for example, Delta T 50, means that if you wanted your bedroom at 18 degrees C, you would need the surface temp of a correctly sized rad at 68 deg mean temp. This is normally taking it that the outside temp will be minus 1 degree Centigrade.

Using a mear calculator and the room size you give I would be looking around 5100 Btu,s /hr Heat requirements
This is possibly a little oversized but it is what I have always used and it will cope better with a bad winter. If you are very exposed, add 10%. It is not an exact science so don't get hung up on exact measurements, there are many other factors that will effect these calculations, such as you over sizing the room.

That requirement given is my own personal way of doing it using the method I have always used and the sizes you gave. Others may disagree, or indeed have different methods and reach different results but they should be similar.

I hope this helps you.

 

[David Stellaman]

Basically it is the difference between the room temp and surface of rad temp.
Have a look at what the rad manufacturers give as delta T when they give the output. The delta is symbolised with a triangle as you probably know. So it will be a triangle with a number. The number will be temp diff in Centigrade. So for example, Delta T 50, means that if you wanted your bedroom at 18 degrees C, you would need the surface temp of a correctly sized rad at 68 deg mean temp. This is normally taking it that the outside temp will be minus 1 degree Centigrade.

Using a mear calculator and the room size you give I would be looking around 5100 Btu,s /hr Heat requirements
This is possibly a little oversized but it is what I have always used and it will cope better with a bad winter. If you are very exposed, add 10%. It is not an exact science so don't get hung up on exact measurements, there are many other factors that will effect these calculations, such as you over sizing the room.

That requirement given is my own personal way of doing it using the method I have always used and the sizes you gave. Others may disagree, or indeed have different methods and reach different results but they should be similar.

I hope this helps you.

Thanks again for the reply. I feel like I'm getting somewhere now. I will email the manufacturer for the Delta number. It was unusual that there were no specs when the boxed rad was delivered, only the fitting measurements.The fitter commented on this.

Dave

 

[gassafe]

I always explain to the Customer that these rads aren't as efficient as a regular convector rad!

This comes after having fitted 2 in one house & having to change them lol, they were like hot water bottles on the wall, hot to touch but no heat deflected into room!

 

[tamz]

At the end of the day i'm afraid this comes down to you.
They gave the information you required ie 4705btu @60ºΔT which means 4705btu at a mean water to air temperature of 60º. This is not a viable way of calculating anything as generally the air temp will be 20º+(bedrooms used to be 18º but these days a bedroom is expected to be as warm as a lounge) and the mwt will be anything between 76 (max unless poorly installed) to <50º with a condensing boiler. This means your ΔT is between 30 and 56 and the lower the ΔT the lower the output.
If you contact the manu they will give you correction factors that are applied to the given outputs to give you the outputs at any given ΔT eg at a ΔT of 50 the correction factor may be 0.78 so the 4705 btu drops to 3670btu
Btw dark colours radiate more heat but unfortunately radiators radiate very little. They convect heat. An example of this is hold your hands 6" from your radiator and you won't feel much heat but hold your hands 6" from an open fire and you won't keep them there long.
There is a bit more to the heating game than can be looked up on an internet unless you know exactly what you are looking for.
In the meantime a couple of these will help with with radiation heatloss [DLMURL="http://www.sportsdirect.com/lee-cooper-cooper-winter-beanie-hat-mens-909015?colcode=90901503"]Lee Cooper | Lee Cooper Winter Beanie Hat | Men's Winter Accessories[/DLMURL]

 

[David Stellaman]

Totally take your point Tamz about the Internet and would never attempt to do a heating related job myself. Dug the hot water bottle out last night and it burst because the rubber had perished:grin: will call in a heating engineer to give the whole system the once over and see if there is anything that can be tweaked. If nothing can be done will take advice on what to fit in its place and I will go back to the place of purchase to see if some deal can be done.
I appreciate any time you guys have given me, as I say I would never attempt anything like this myself but do like to understand a little about what others do.

I will post the outcome so that others in a similar situation can read it and not take up anyone else's time.

Dave

 

[oz-plumber]

Question:

Do you have a condensing boiler and what temperature is the flow set to?

If we had that information, correction factors could be given and the rated heat output could be made.

The way I read the figures you have been given is:

90C Flow, 70C Return = Mean water temp 80C.
Less room temp 20C

Delta T = 60 C

 

[David Stellaman]

Question:

Do you have a condensing boiler and what temperature is the flow set to?

If we had that information, correction factors could be given and the rated heat output could be made.

The way I read the figures you have been given is:

90C Flow, 70C Return = Mean water temp 80C.
Less room temp 20C

Delta T = 60 C

Hi Oz, I will get those details later when I'm home. Are you saying that if those figures are correct that the radiator should be performing better, even after three hours with the boiler temp set to max, the room is not even warm, just the chill taken off it. I need to decide a. Whether to bite the bullet and replace the radiator with a same design but much higher output.b. Replace it with a more traditional radiator which will involve much more invasive prep work for the pipework or c. Move out...:mad2:

Dave