Ccts conversion and weather comp.

[gingalig]

Aplologies as I've asked before, but would like to clarify, I,ve been asked to convert from oil (Open vent) to lpg sealed, using a viessmann 111w, its being fitted to approx 3kw ufh with electronic actuators at the manifold for each ufh loop, and 7 rads on microbore. My plan is to use close coupled Tees at the boiler with a bypass, (primary circuit) use the boiler pump as a shunt, connect a second pump and zone valve for the secondary circuit (radiator system) and repeat for the ufh with pump, zone valve and blending valve. The system has been power flushed, all the ufh is new and the majority of flow and return primary pipework to the rads is being replaced, My other concern was complying with boiler plus, I usually fit weather comp although I have been informed that adjusting the heat curve will be ok, Any thoughts on the set up would be appreciated. In future I think I will be using a LLH.

 

[ShaunCorbs]

Sounds fine can’t you just roughly draw it out also you won’t need a bypass

 

[SJB060685]

Sounds fine can’t you just roughly draw it out also you won’t need a bypass

If using close coupled tees or a LLH you don't need a bypass yeah Shaun?

 

[ShaunCorbs]

If using close coupled tees or a LLH you don't need a bypass yeah Shaun?

correct unless your programming pump over run on your secondary circuits and your using port valves etc

 

[SJB060685]

correct unless your programming pump over run on your secondary circuits and your using port valves etc

Is there anything stopping using the loop between boiler and llh for pump overrun?

 

[ShaunCorbs]

Is there anything stopping using the loop between boiler and llh for pump overrun?

no that’s fine to do

 

[SJB060685]

Ok, thanks buddy 👍. Never installed a LLH, in fact we did little installing and I've only come across a few of them in the domestic oil scene.

 

[gingalig]

Sounds fine can’t you just roughly draw it out also you won’t need a bypass

Hi, Shaun, please excuse the scrawl. I was thinking something like this. If it looks wrong please let me know.
The ufh is all electronic actuators which made me question the need for a zone valve but it my well be best to include. I was also thinking mag filter and auto air release valve on the loop between boiler and secondary supply.

 

[ShaunCorbs]

Looks fine 35mm tube ??

mans with ufh always include a port valve

 

[SJB060685]

Looks fine but boiler side cct is only 4x the dia and not 8 unless you’ve read it specially ?

Shaun I thought all CCT were 4 x pipe diameter centre to centre? Where or when would it be 8?

 

[ShaunCorbs]

Shaun I thought all CCT were 4 x pipe diameter centre to centre? Where or when would it be 8?

miss read it myself 8x min to the elbow /straight pipe

 

[SJB060685]

miss read it myself 8x min to the elbow /straight pipe

Ok, so to clarify all CCT 4 x OD centre to centre and a minimum of 8 x OD of straight pipe before any elbow?

 

[gingalig]

Looks fine 35mm tube ??

mans with ufh always include a port valve

The circuit from the boiler to the secondary circuit it going to be as small as I can get away with in terms of space, I was hoping to use 22mm to tie into the existing 22mm flow and returns from the boiler to the radiator circuit and 22mm on the manifold, the system is relatively small although I wouldnt want to restrict demand.

 

[ShaunCorbs]

The circuit from the boiler to the secondary circuit it going to be as small as I can get away with in terms of space, I was hoping to use 22mm to tie into the existing 22mm flow and returns from the boiler to the radiator circuit and 22mm on the manifold, the system is relatively small although I wouldnt want to restrict demand.

sorry I mean on the cct loop

 

[gingalig]

sorry I mean on the cct loop

Hi, 35mm seems huge, do you mean the tees themselves and then scaled down, or the whole loop, It's my 1st cct system, hence so many questions and so little knowledge.

 

[ShaunCorbs]

Hi, 35mm seems huge, do you mean the tees themselves and then scaled down, or the whole loop, It's my 1st cct system, hence so many questions and so little knowledge.

yea need to go at least one size up on the tees

 

[SJB060685]

yea need to go at least one size up on the tees

Why is that Shaun mate?

 

[gingalig]

yea need to go at least one size up on the tees

Thank you, Shaun much appreciated.
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Why is that Shaun mate?

Apologies, many thanks to both of you. I appreciate the advice and sharing on this forum more than any other.

 

[ShaunCorbs]

Why is that Shaun mate?

so there’s room for it to mix and crossflow

 

[SJB060685]

Ok. So say you got CCT and say 4 secondary circuits, say the secondary loop is 28mm, sized to carry full load, you would install 35mm boiler primaries and Tee's to allow this mixing and cross flow? Sorry I'm just trying to familiarise it in my head

 

[ShaunCorbs]

Ok. So say you got CCT and say 4 secondary circuits, say the secondary loop is 28mm, sized to carry full load, you would install 35mm boiler primaries and Tee's to allow this mixing and cross flow? Sorry I'm just trying to familiarise it in my head

boiler primaries depending on load could be 22mm then just upside the tee eg 35mm as your ring is 28mm etc if your ring is 22 you could use 28mm tees but wouldn’t go above 50kw with 28mm tees

 

[gingalig]

boiler primaries depending on load could be 22mm then just upside the tee eg 35mm as your ring is 28mm etc if your ring is 22 you could use 28mm tees but wouldn’t go above 50kw with 28mm tees

Just to clarify, the boiler primaries

boiler primaries depending on load could be 22mm then just upside the tee eg 35mm as your ring is 28mm etc if your ring is 22 you could use 28mm tees but wouldn’t go above 50kw with 28mm tees

Hi, Just to clarify the primaries are 22mm and the loop was going to be in 22mm the boiler max output is 35kw although I would be ranging it down. If I up the tees to 28mm from the boiler to the loop would this be ok, also would the tees for the secondary supply also be in 28mm or would they be ok using 22mm, sorry for all the questions just trying to get it clear before I install. Many thanks.

 

[ShaunCorbs]

Just looking at your drawing again why is the boiler and rads got ccts ?

 

[gingalig]

Just looking at your drawing again why is the boiler and rads got ccts ?

When I first asked the question a while ago on a different thread about mixing microbore on the radiator circuit and UFH you had actually suggested it. I had a concern that the different demands could be counter productive. If I can climb back into my comfort zone and go for a straight install then that would be a whole lot less worry inducing, although my understanding of CCT,s has greatly improved and its been an interesting journey, I will install using them or an LLH at some point. Do you think there is no need for them ?

 

[ShaunCorbs]

Don’t need to do it on the boiler or rad circuit unless you have pump on pump so remove the pump on the rad circuit and you will be fine

but keep your cct on the underfloor heating