Reverse Circulation Central Heating

[James_Smith789]

Hi folks,

I am having a problem with reverse circulation. I have attached a photo. The insulated pipe making the tee is the H/W return. Pipe feeding in on the left is the Rad return and the pipe to the right continues to the boiler. Because the pipe to the right has a tight bend i wondered if this could be creating increased resistance and forcing hot water up the rad return? I am a DIYer so really haven't a clue.

 

[Moffski72]

Hi folks,

I am having a problem with reverse circulation. I have attached a photo. The insulated pipe making the tee is the H/W return. Pipe feeding in on the left is the Rad return and the pipe to the right continues to the boiler. Because the pipe to the right has a tight bend i wondered if this could be creating increased resistance and forcing hot water up the rad return? I am a DIYer so really haven't a clue.

View attachment 30972

Has this just started or has it always done it?

 

[James_Smith789]

Has this just started or has it always done it?

I have only noticed it this summer. Boiler was replaced last year and some of the pipework. Very old house and very old pipework. Hot water only being on leads to most radiators being warm. The rad return in the picture is absolutely roasting when the hot water is on.

 

[Moffski72]

I have only noticed it this summer. Boiler was replaced last year and some of the pipework. Very old house and very old pipework. Hot water only bring on leads to most radiators being warm. The rad return in the picture is absolutely roasting when the hot water is on.

Need a bit more info about the system and the new boiler...do you know if its a y-plan or s-plan?
Was the system flushed/cleaned with chemicals when the new boiler was fitted?

 

[James_Smith789]

Need a bit more info about the system and the new boiler...do you know if its a y-plan or s-plan?
Was the system flushed/cleaned with chemicals when the new boiler was fitted?

Yes, it was flushed. I believe it is a s-plan. Pump fitted on return system. Pressurised system now, previously used water tank. Header tank in loft.

Not sure if any of that helps?

 

[Moffski72]

Can you post a few more pics of pipework, showing boiler and pump, whatever you can see really...

 

[Best]

Pump needs to be fitted on the part of return pipe that is last to go to boiler. Not teed off in the flow circuit of pump.
Is yours done this way?
You really should be getting the installers back to fix their work.

 

[James_Smith789]

Pump needs to be fitted on the part of return pipe that is last to go to boiler. Not teed off in the flow circuit of pump.
Is yours done this way?
You really should be getting the installers back to fix their work.

 

[Moffski72]

Yep, from that picture I would say it's not pipes up right, cylinder connection needs to be the last tee before the boiler/pump, and looking at that, it's not. Get your installer back

 

[James_Smith789]

Yep, from that picture I would say it's not pipes up right, cylinder connection needs to be the last tee before the boiler/pump, and looking at that, it's not. Get your installer back

Sorry, can i check what you mean by 'its not pipes up right'? as in its nothing to.do with the pipes on the right hand side of the picture? If you ignore the pipes on the right (which incudes another rad return which is cool and not hot) why would there be reverse circulation as the cylinder return pipe is after the rad return pipe? Could it be related to the 'tight' downward bend and hence the water finds it easier to go up.the rad return to the left?

 

[James_Smith789]

Pump needs to be fitted on the part of return pipe that is last to go to boiler. Not teed off in the flow circuit of pump.
Is yours done this way?
You really should be getting the installers back to fix their work.

From what I can see it is (Upstairs) rad return, hot water return, (downstairs ) rad return, pump and then bypass/safety closest to boiler.

 

[Moffski72]

Apologies for typo...should have been 'not PIPED up right'...as in incorrect. The tee that is directly above the pump should be the tee off for the cylinder return...its not though, and this is the problem. It creates a route for the water to circulate, bypassing the heating zone valve on the rad circuit and allowing the reverse circulation effect, heating up your rads when the hot water is on. The best solution is to alter the pipework so that the cylinder connection is the last one before the pump.