Scratching my head (open vent)

[Mranon1989]

I need to tap in to the central heating due to an extension with underfloor heating that’s gone in. I want to be more than sure before tapping into the system due to its complexity and being an open vent I’m going to freeze the pipes I need to, so I can work on them. I was hoping to double check on here to avoid making a mistake.

The two 28’s I believe are the flow and returns for the cylinder and the two 22’s on the left are for the Heating. I noticed there’s a tee branching off and running alongside the heating pipes. Is that a bypass or the actual vent for the heating? Never worked on these systems before so sorry if I come across as clueless.

I think I’ve attached a photo of the boiler. Thanks!

 

[SimonG]

Good luck

 

[EvilDrPorkChop]

UFH on open vent, forget it

 

[Mranon1989]

Good luck

Really?

 

[SimonG]

Really?

No

 

[Mranon1989]

No

I was being sarcastic as well, if you can give it learn to take it.

 

[SimonG]

I was being sarcastic as well, if you can give it learn to take it.

Shame I wasn't first time, petal.

 

[Mranon1989]

Mwah

 

[Mranon1989]

UFH on open vent, forget it

Had problems in the past I take it?

 

[EvilDrPorkChop]

Had problems in the past I take it?

IMO open vented and UFH is just bad practice. Air locks, more risk of dirt in system (Imagine a blocked UFH circuit!), more noisy. TBH running UFH off that boiler anyway wouldn't be ideal, they need a new boiler and system upgrade! UFH running more often, the HW is always going to be on due to the gravity. There's loads of reasons for suggesting an upgrade is due.

 

[Mranon1989]

IMO open vented and UFH is just bad practice. Air locks, more risk of dirt in system (Imagine a blocked UFH circuit!), more noisy. TBH running UFH off that boiler anyway wouldn't be ideal, they need a new boiler and system upgrade! UFH running more often, the HW is always going to be on due to the gravity. There's loads of reasons for suggesting an upgrade is due.

I agree with you, I did suggest ages ago but they were adamant on keeping the same system. I just want to tap into the right pipes, get it running and walk away to be honest.

 

[EvilDrPorkChop]

I agree with you, I did suggest ages ago but they were adamant on keeping the same system. I just want to tap into the right pipes, get it running and walk away to be honest.

To be honest you should have advised them that UFH isn't suitable for that system and refused to do it.

And in terms of getting it going and walking away, I don't think it'll ever work properly. You're opening a can of worms, that I wouldn't be opening

 

[Mranon1989]

Well no mention of underfloor not working on open vent systems in the guides used throughout the industry and no one willing to just tell me so I’m just figure it out myself. Thanks for nothing. Lovely peeps

 

[Riley]

Edited that for you OP

 

[SimonG]

Pope on a soap, thought the op was a diyer.

Ye gads!!

 

[Mranon1989]

Edited - Keep it on plumbing

 

[Riley]

Seriously stop now

 

[Gasinspect]

I suppose one of these, with a three zone programmer, and a magnaclean on the flow to it, would work, tap off the flow and return close to the boiler before any of the other connections. Take boiler panels off to double check f r.
JG SPEEDFIT UNDERFLOOR HEATING MIXING VALVE & PUMP UNIT (screwfix 9593P)

 

[Ready Steady Gas]

There's no reason it wouldn't work, but that said you may not get the same efficiency as a sealed system.

There no harm in putting the infrastructure of underfloor heating in and trying with an existing system, you can update the rest of the system at a later date if needed.

I put a coil down in a screened floor at my dads about 15 years ago and it simply runs of the existing open vented system with a back boiler.

Has never had any problems over that time, just remember to use plenty of inhibitor in open vented heating systems when every you introduce fresh water back into the system, very important.

 

[Sparkgap]

I need to tap in to the central heating due to an extension with underfloor heating that’s gone in. I want to be more than sure before tapping into the system due to its complexity and being an open vent I’m going to freeze the pipes I need to, so I can work on them. I was hoping to double check on here to avoid making a mistake.

The two 28’s I believe are the flow and returns for the cylinder and the two 22’s on the left are for the Heating. I noticed there’s a tee branching off and running alongside the heating pipes. Is that a bypass or the actual vent for the heating? Never worked on these systems before so sorry if I come across as clueless.

From the looks of it small pipe is cold feed, larger pipe off the one going to the pump is vent. Pump line and the pipe just above it are heating circuit. I assume someone stuck a pump and valve on the old gravity circuit to the cylinder and since the whole system now appears to be pumped you could take the UFH connections off these between the boiler and the control valve if it's easier.
I don't see any problem running UFH off a vented system provided you take precautions to keep it clean and don't have a stupid low system head.