Any plumbers/CH engineers in the house? - BMW 3-Series (E90 E92) Forum

Hotcoupe · 12-14-2012, 07:23 AM

I've got a problematic rad,there's a marked difference in temperature between the bottom and the top of the rad,the top being hotter.

I've had the rad off after isolating at the valves,and drained it down.
I then took it outside to flush it through as I thought there might be a load of black shite in the bottom,but that wasn't the case.

I've now turned all the other rads off in the vain hope that this measure might push through what could be an airlock?

That doesn't seemed to have worked either

Any other ideas/tips chaps ?

Ta muchly.

A_P · 12-14-2012, 07:36 AM

I know this might be a stupid suggestion. As I am no plumber, and besides you may have already done this.

Switch the broken radiator ( lounge) for a good one ( kitchen). Then check to see if the problem persists, if it does then obviously it would mean there is a problem with piping.

And if it is 100% not working then I am not sure on how to fix, possibly replace if not expensive? From somewhere like Screwfix?

Sorry not much help I know. but hey.

dotmit · 12-14-2012, 07:36 AM

Odd that the top is hotter. If it was an airlock I'd expect it to be the other way round.

Could be that the radiator has corroded inside and is now just a big empty tank instead of having pipes through it, and so convection is naturally making the top hotter? Long shot I know!

Hotcoupe · 12-14-2012, 07:42 AM

Quote:

Originally Posted by A_P

I know this might be a stupid suggestion. As I am no plumber, and besides you may have already done this.

Switch the broken radiator ( lounge) for a good one ( kitchen). Then check to see if the problem persists, if it does then obviously it would mean there is a problem with piping.

And if it is 100% not working then I am not sure on how to fix, possibly replace if not expensive? From somewhere like Screwfix?

Sorry not much help I know. but hey.

The rads not broken as such,just not working correctly,it's not even that old.

Cheers for the suggestions though

Jedimindtrix · 12-14-2012, 08:44 AM

Swap the rad for a new one you've tried everything that I would do, try and get like for like so no pipe work alteration is required.

Remember to add some inhibitor into the system afterwards.

alzieboy · 12-14-2012, 09:08 AM

Try balancing the system, shut some rads off that are near to the offending radiator on the lockshield valves, you will need to pull off the caps and use a small adjustable spanner, ( these are the valves on radiator ) then see if the radiator heat coverage improves , if it does then start to slightly open all the lockshield valves untill all radiators seem about the same Temp.

Give it a go.

briers · 12-14-2012, 09:13 AM

Three things came to mind, balancing, faulty TRV, try pump speed on highest setting if not already so. With a note that pump speed 3 can sometimes introduce air which needs bleeding from furthest rad every few weeks. Bleed with system cold.

I'm not a heating engineer so only guessing, but as you said you turned off all other rads, i'm not so sure my thoughts count now.

John320d · 12-14-2012, 11:36 AM

are the rad conns. tboe. top and bottom opposite ends? if so, the flow pipe could in the bottom of the rad and the return water exiting via the top connection. this could cause this problem. retired heating eng.

Hotcoupe · 12-14-2012, 03:11 PM

Cheers for all the suggestions Guys

,it's now sorted.

A_P · 12-14-2012, 03:20 PM

For reference, what was the solution? Glad you got it sorted.

Hotcoupe · 12-14-2012, 03:32 PM

Quote:

Originally Posted by A_P

For reference, what was the solution? Glad you got it sorted.

Left all the other rads off,and whacked the pressure up on the boiler to 3bar!

The increase in pressure pushed out the airlock in the rad,and the surplus went out the blow off valve

The boiler went into limp mode initially,but it soon settled down to 1.5bar and 550lbs torque

A_P · 12-14-2012, 03:35 PM

LOL without a remap too.

Awesome work. So you were right all along.

12-14-2012, 07:23 AM	#1
Hotcoupe Major General Drives: Don't know yet! Join Date: Jul 2007 Location: UK Posts: 5,872 iTrader: (2) Garage List November 2008 335D ... [4.17] 2007 335D [0.00]	Any plumbers/CH engineers in the house? I've got a problematic rad,there's a marked difference in temperature between the bottom and the top of the rad,the top being hotter. I've had the rad off after isolating at the valves,and drained it down. I then took it outside to flush it through as I thought there might be a load of black shite in the bottom,but that wasn't the case. I've now turned all the other rads off in the vain hope that this measure might push through what could be an airlock? That doesn't seemed to have worked either Any other ideas/tips chaps ? Ta muchly. __________________ ================================= Never argue with an idiot on the internet. He will drag you down to his level and beat you with experience.
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12-14-2012, 07:36 AM	#3
dotmit Private First Class Drives: E93 325i \| K46 S1000RR Join Date: Nov 2012 Location: EC3 Posts: 136 iTrader: (0)	Odd that the top is hotter. If it was an airlock I'd expect it to be the other way round. Could be that the radiator has corroded inside and is now just a big empty tank instead of having pipes through it, and so convection is naturally making the top hotter? Long shot I know! __________________ I'm new. Go easy on me

12-14-2012, 08:44 AM	#5
Jedimindtrix Private First Class Drives: Alpina D3 MT Join Date: Oct 2012 Location: Washington, North East Posts: 192 iTrader: (0)	Swap the rad for a new one you've tried everything that I would do, try and get like for like so no pipe work alteration is required. Remember to add some inhibitor into the system afterwards. __________________ Currently driving an Alpina-D3 MT, Sapphire black, Classic Alloys wrapped in PS2's, Full Alpina interior trim, Black Grilles, Blackline tail lights and zymol'ed once a month.

12-14-2012, 03:11 PM	#9
Hotcoupe Major General Drives: Don't know yet! Join Date: Jul 2007 Location: UK Posts: 5,872 iTrader: (2) Garage List November 2008 335D ... [4.17] 2007 335D [0.00]	Cheers for all the suggestions Guys ,it's now sorted. __________________ ================================= Never argue with an idiot on the internet. He will drag you down to his level and beat you with experience.

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12-14-2012, 07:36 AM	#2
A_P Lieutenant Colonel Drives: E46 M3 Join Date: Mar 2012 Location: South East Posts: 1,698 iTrader: (0)	I know this might be a stupid suggestion. As I am no plumber, and besides you may have already done this. Switch the broken radiator ( lounge) for a good one ( kitchen). Then check to see if the problem persists, if it does then obviously it would mean there is a problem with piping. And if it is 100% not working then I am not sure on how to fix, possibly replace if not expensive? From somewhere like Screwfix? Sorry not much help I know. but hey.

12-14-2012, 09:08 AM	#6
alzieboy Second Lieutenant Drives: 318d LCI exclusive edition Join Date: Feb 2012 Location: Norfolk Posts: 237 iTrader: (0)	Try balancing the system, shut some rads off that are near to the offending radiator on the lockshield valves, you will need to pull off the caps and use a small adjustable spanner, ( these are the valves on radiator ) then see if the radiator heat coverage improves , if it does then start to slightly open all the lockshield valves untill all radiators seem about the same Temp. Give it a go.

12-14-2012, 09:13 AM	#7
briers Ben Drives: XFR Join Date: May 2010 Location: Midlands,UK Posts: 1,880 iTrader: (0)	Three things came to mind, balancing, faulty TRV, try pump speed on highest setting if not already so. With a note that pump speed 3 can sometimes introduce air which needs bleeding from furthest rad every few weeks. Bleed with system cold. I'm not a heating engineer so only guessing, but as you said you turned off all other rads, i'm not so sure my thoughts count now.

12-14-2012, 11:36 AM	#8
John320d Private First Class Drives: BMW 320d E93 Join Date: Dec 2009 Location: Manchester UK Posts: 108 iTrader: (0)	are the rad conns. tboe. top and bottom opposite ends? if so, the flow pipe could in the bottom of the rad and the return water exiting via the top connection. this could cause this problem. retired heating eng.

12-14-2012, 03:20 PM	#10
A_P Lieutenant Colonel Drives: E46 M3 Join Date: Mar 2012 Location: South East Posts: 1,698 iTrader: (0)	For reference, what was the solution? Glad you got it sorted.

12-14-2012, 03:35 PM	#12
A_P Lieutenant Colonel Drives: E46 M3 Join Date: Mar 2012 Location: South East Posts: 1,698 iTrader: (0)	LOL without a remap too. Awesome work. So you were right all along.