Flow in at top o bottom?

[solarCH]

We have an install with all main tubing in a false ceiling, so we have to drop down to the radiators. Is there really any advantage to conecting the flow in at the top of the radiator?

Normally we come up from floor and connect flow/ return to each end at the bottom but coming down we could connect at the top to flow in and return from the bottom. I read a comment that this is more efficient but not seen any data to support this. Can anyone pls elaborate? Thanks

 

[Ray Stafford]

TBOE - (top & bottom opposite ends) is how they test the rads to get the outputs published, and IIRC its gives about 5% more output from the rad than BOE (Bottom, opposite ends).

 

[kay-jay]

yes tboe is the best way in terms of performance, just looks naff!

 

[stevetheplumber]

yes tboe is the best way in terms of performance, just looks naff!

unless your using cast antique collum rads when it will look the best

 

[Roger Welton]

unless your using cast antique collum rads when it will look the best

Especially when done using steel pipe and nice brass valves.

 

[Scott_D]

Sounds like a non domestic job?
Best to check the job spec if you have one. You would want to have to go back and change it.

 

[doitmyself]

TBOE - (top & bottom opposite ends) is how they test the rads to get the outputs published, and IIRC its gives about 5% more output from the rad than BOE (Bottom, opposite ends).

BS EN442 specifies TBSE (same end) for testing radiators; it's only about 2% more than BOE!

 

[solarCH]

BS EN442 specifies TBSE (same end) for testing radiators; it's only about 2% more than BOE!

For panel radiators or element based units with 14+

 

[solarCH]

doing the design now and some TRV need to go at the top of the rad and a few will leave horizontal TRV sicking out into the window space, just waiting to be knocked off..

If we put the TRV at the top at 45 degrees, can we just compensate for the radiator heat buy raising the temp from 20 to say 24/25?

 

[doitmyself]

If we put the TRV at the top at 45 degrees, can we just compensate for the radiator heat by raising the temp from 20 to say 24/25?

The temperatures which each number represents is just approximate. Most TRV's can be set between numbers, so it will be a case of trial and error until you find the setting which provides the required level of heat.

TRVs should be set and then left; opening a TRV to Max does not heat a room up any quicker.

 

[solarCH]

Thanks everyone- what about cool spots with TBOE? Does anyone have any experience of reducing these with slower flow rates (ie a temp drop of 20 or even 25 across the rad?)

 

[solarCH]

BS EN442 specifies TBSE (same end) for testing radiators; it's only about 2% more than BOE!

Found an interesting comparison the various configurations on page 120 of "Heating services in buildings : design, installation, commissioning & maintenance I by David F Watkins. ISBN 978-0-470-65603-7"

You can see excerpts online here.

Lists BOE as 5-20% less efficient than TBSE, TBOE as 5-10%. Rad type (panel or element) and flow rates are not specified.

 

[DirksPlumbing]

Thanks everyone- what about cool spots with TBOE? Does anyone have any experience of reducing these with slower flow rates (ie a temp drop of 20 or even 25 across the rad?)

In well insulated premises you can cause over shooting with a riding connection (BOE). As the radiator will layer much less than on TBOE/TBSE.

TBSE has major disadvantages on low but long rads as the cross flow lifts the return unnecessary.

Best option in my opinion is valved rads, Stelrad does do them pretty well engineered.

 

[WHPES]

I disagree about it looking naff. Yes if you put the tubes going straight up and down it does but if you take a bit of time you can put a few bends in and hide most of the pipe behind the edge of the radiator making a very neat job.

 

[Ray Stafford]

BS EN442 specifies TBSE (same end) for testing radiators; it's only about 2% more than BOE!

Just checked, and I stand corrected! Was is always TBSE? I could have sworn it used to be TBOE - perhaps I am just getting senile.

 

[doitmyself]

Was is always TBSE? I could have sworn it used to be TBOE.

Maybe you are thinking of the earlier BS3528?