Radiator replacement - should we go for higher BTU than needed?

[jker]

Looking for some advice on radiator BTU sizing.

We’re looking to replace a standard radiator with a vertical one in our upstairs spare bedroom/home office because it works better for the layout of the room.

Using online BTU calculators, the room seems to need around 2550–2650 BTU.

The plumber gave us a couple of options for the dimensions we're looking at.

- an aluminium vertical radiator rated around 2800 BTU (single panel style)

- or a steel vertical radiator around 3800 BTU (double panel)

The 2800 BTU would be enough, but would it be better to oversize and go with the 3800 BTU option?

Main thing I’m unsure about is whether 3800 BTU would be considered too oversized for a room like this, or whether going a bit bigger is generally recommended?

We have a normal combi boiler.

Thanks

 

[HERTS P&D]

I would always over size as you can always turn them down. You can't turn up what you don't have.

Andy

 

[denso13]

Go larger with a vertical, fit a TRV of it doesn't have one and that will limit the room temperature l.

 

[dilalio]

I would always over size as you can always turn them down. You can't turn up what you don't have.

Andy

Words out of my mouth

 

[jker]

Words out of my mouth

Thanks i ve heard that was well but wasn't sure if the other radiator was a bit too much.

Do you recommend getting the radiators through the plumber directly or looking at different options and buying online?

 

[Madrab]

If you are looking at designer tubular type radiators then be aware of how they work, compared to normal convection type radiators. Albeit their output may be similar, the way they heat the space (air) in the room isn't the same, they are a lot less efficient at space heating than traditional type rads as they don't convect very well

Anything beyond say 4-5 feet will take a lot longer to warm up and they can take twice as long to heat the space than traditional types.

 

[dilalio]

Do you recommend getting the radiators through the plumber directly or looking at different options and buying online?

Up to you, but I'm a plumber and when customer buys it, they carry the can for any problems with the product.

Either way, make sure you flush them out before fitting... Many of them are full of burrs, rust and manufacturing debris

 

[jker]

Up to you, but I'm a plumber and when customer buys it, they carry the can for any problems with the product.

Either way, make sure you flush them out before fitting... Many of them are full of burrs, rust and manufacturing debris

Thanks, we would get a plumber to install it anyway so maybe better to go with one supplied directly by then, I hadn't really thought about us having to deal with potential problems if buying directly.

So do you think oversizing and going to for 3800 BTU instead of 2700 would be better idea?
Our house is from 1990s and have a normal combi boiler. Going to bigger BTU radiators wouldn't cause any problems with the boiler having to deal with more?

We would get valves installed so can always turn them down depending on how well they heat the room.

 

[denso13]

So do you think oversizing and going to for 3800 BTU instead of 2700 would be better idea?

Yes, combi will cope just fine.

 

[jker]

If you are looking at designer tubular type radiators then be aware of how they work, compared to normal convection type radiators. Albeit their output may be similar, the way they heat the space (air) in the room isn't the same, they are a lot less efficient at space heating than traditional type rads as they don't convect very well

Anything beyond say 4-5 feet will take a lot longer to warm up and they can take twice as long to heat the space than traditional types.

Thanks for the info.

We are also looking to replace the radiator in our living room. I think previously they had a big horizontal radiator but previous owner got a vertical radiator that wasn't really big for the size of the room. Plumber said getting a bigger vertical one should make a difference. We did notice it not really warming up the room as much but thought maybe it was because it was too small.

The layout of the room isn't the best and if we wanted to go for a horizontal one, we would need to have it behind where the sofa is and I thought then it would block the heat anyway if the sofa is in front of it? Do you think that could be a better option than a bigger vertical radiator?

 

[denso13]

First thing is to get the correct, or bigger, radiator output for the heat loss in the room. The style and placement is the next choice, it might not matter so much in a lounge therefore a modern horizontal one may suit you.

However, I know some don't like verticals, but I have never had an issue with them. I have two in my own house that work perfectly well when sized/installed properly.

 

[endecotp]

We’re looking to replace a standard radiator

Does the existing radiator keep the room warm enough? What is its output? (Measure it, and find a similar new one.)

 

[jker]

Does the existing radiator keep the room warm enough? What is its output? (Measure it, and find a similar new one.)

Yeah it does, but it's an old radiator (probably from the mid 90s when the house was built) so not sure what the output would be :/

 

[Madrab]

The trouble with these new designer tubular radiators is the way they heat.

Classic type white radiators primarily use convection to heat the air that is drawn up through the radiator/fins and then out into the room, that cycle continues and heats the room quickly and efficiently. Their output is typically ~ 90% convection > 10% radiation
Column tubular type rads don't convect to anywhere near the same level. Typically ~ 20% convection > 80% radiation - therefore they take a awful lot longer to heat the space anywhere beyond their radiant range, which is typically 5-6ft
Older classic design cast iron/steel type column rads are more efficient than the modern tubular types, due to their specific construction but even then they are only about 40% convection > 60% radiation.

Column/tubular rads can work, especially in smaller spaces with lower ceilings but they do need to be sited and designed into the space properly. Larger spaces need more of them and need to be sized accordingly, to heat the space any where near a efficiently as classic types. I have found they cannot be sized by comparing them to classic types rad outputs.

£ for £ they aren't the best TBH.

 

[jker]

The trouble with these new designer tubular radiators is the way they heat.

Classic type white radiators primarily use convection to heat the air that is drawn up through the radiator/fins and then out into the room, that cycle continues and heats the room quickly and efficiently. Their output is typically ~ 90% convection > 10% radiation
Column tubular type rads don't convect to anywhere near the same level. Typically ~ 20% convection > 80% radiation - therefore they take a awful lot longer to heat the space anywhere beyond their radiant range, which is typically 5-6ft
Older classic design cast iron/steel type column rads are more efficient than the modern tubular types, due to their specific construction but even then they are only about 40% convection > 60% radiation.

Column/tubular rads can work, especially in smaller spaces with lower ceilings but they do need to be sited and designed into the space properly. Larger spaces need more of them and need to be sized accordingly, to heat the space any where near a efficiently as classic types. I have found they cannot be sized by comparing them to classic types rad outputs.

£ for £ they aren't the best TBH.

Thanks. Our living room is 4x4m with ceiling height of 2.3 so on the low side.

Do you reckon having a horizontal radiator behind the sofa instead could be a better option, and if so what gap should we leave between it and the sofa.