How is a 2 zone heating system suppose to be piped

[Inverness]

Hi. A new house regulation for a 2 zone heating system because it's bigger that 150sqm.

I'm I right in saying zone 1 should be all of the downstairs radiators and zone 2 all of the upstairs radiators ?

I have thermostat room programmer down the stairs and another one upstairs.
I think the two rads that are in the same room as the room stat have no trv but everywhere else has trvs except the upstairs hallway way? Would this reason be acting like a bypass?? When the downstairs heating is running and zone 2 is off. The hallway upstairs rad is on? The upstairs hallway rad is o

 

[fowlerboi]

It would be upstairs and downstairs zones.

The rooms that have the thermostat in wouldn't have TRVs as they would prevent the thermostat doing its job properly. Regardless of this no radiators up stairs should be getting hot when the downstairs is on. The only exception to this will be reverse circulation which would normally make it warm and not red hot like the others that are actually on. Hopefully they provided some means to prevent reverse circulation

Is the upstairs room stat in the hallway?

If you check between the pump and the zone valves there should be a bypass, if there isn't one then they may have piped the upstairs radiator like a bypass. If they did then they are idiots.

 

[Inverness]

Thank you.

I'll check again tomorrow how hot it gets..

If it is due to reverse circulation how easy is it to fix?

 

[Inverness]

Thank you.

I'll check again tomorrow how hot it gets..

If it is due to reverse circulation how easy is it to fix

 

[Inverness]

Do you mean by reverse when zone 1 is returning back to the boiler the hallway upstairs radiator is stealing some of the heat?

 

[ShaunCorbs]

Where the room stat is you can’t have a trv on the rads in the same room

Chances are they’ve used the same return and teed all the rads return as one instead of running two returns and piping it back to the airing cupboard

Your getting revers circulation

 

[fowlerboi]

I've never fitted a 2 zone heating other than UFH/rads but understand the principle of it. I can't think of a way you could possibly pipe it to prevent reverse circulation without a mechanical prevention. Typically you would have Cyl/UFH/Rads from the boiler on the return as neither the cyl/ufh can reverse circulate but with Cyl/rads/rads you'll always get one reverse the other depending on what order they returned them in. Would swept tee's prevent it?

 

[ShaunCorbs]

Depends if there’s a return that’s rising eg 3rd floor yes I can see that being a problem but if there falling you might get a bit of heat creep on the short bit of return it nothing that bad as it’s on an s plan system

 

[snowhead]

"Should be" and what has actually been done in the new build aren't necessarily the same.

Although, if the there's a rad in the downstairs hall and the upstairs / downstairs are not separated by a door then the downstairs hall rad is going to heat the upstairs hallway / landing when the upper zone 2 is off.

So maybe whoever designed / installed the system put both the downstairs hall and upstairs hallway rads on the same downstairs zone.

Starting with both zones off and all rads cold, if you turn on zone 1 and the upstairs hall rad gets hot quickly, I'd say it's definitely connected to zone 1.
If the upstairs rad eventually gets hot I'd say it's reverse / unintended flow.

If upstairs hall does appear to be connected to zone 1, then either by design or mistake.

 

[Inverness]

Thanks. I was thinking it's by design because it's alot of space for one rad to heat.