CT and VT Secondary Circuits

[cr0ft]

Hi all,

So as most of you know I'm in my new job and trying to get my head around our commercial heating systems. Unfortunately, there is no one there to show me round each system or it's quirks Most of our buildings have no schematics for the plumbing either

Q1 - My understanding of CT and VT circuits is that CT circuits will normally supply overhead radiant heaters etc and VT circuits will supply radiators. The latter will be typically controlled by a weather compensator and the temperature will then be set using what is effectively a three port valve to mix return water on that circuit with flow water going in.

Q2 - On some of our sites we also have permanent and intermittent VT circuits. At this point I got thoroughly confused so if someone who understands larger commercial systems (i.e. hospital size) could explain this I would be grateful.

Thanks for all replies

 

[ShaunCorbs]

Welcome to the fun time there never is drawings even at new buildings, things get added on / taken away and not updated if there were drawings when the place was constructed 1980 etc

Your thinking newish build most com places arnt that fancy and just relay on a stat out side below 15 heating comes on above it doesn't etc

Also some times there arnt delicate services for ct services, there just tee off the vt line with a blending valve and set to a temp for a batch/ room of either over head or fan convectors

Which I guess is the answer to q2 ?

Hope this helps

Also I wouldnt take the markings as bang on

 

[cr0ft]

Thanks. Any idea why one of our larger buildings has 3 lines - CT, permanent VT and intermittent VT?

 

[ShaunCorbs]

Intermittent could be set for a temp range tbh don't know, do you know what's connected to ivt ?

Any chance of a few pics

 

[Scott_D]

Is it a circuit that's only used part of the year?

 

[Sparkgap]

Hi all,

So as most of you know I'm in my new job and trying to get my head around our commercial heating systems. Unfortunately, there is no one there to show me round each system or it's quirks Most of our buildings have no schematics for the plumbing either

Q1 - My understanding of CT and VT circuits is that CT circuits will normally supply overhead radiant heaters etc and VT circuits will supply radiators. The latter will be typically controlled by a weather compensator and the temperature will then be set using what is effectively a three port valve to mix return water on that circuit with flow water going in.

Q2 - On some of our sites we also have permanent and intermittent VT circuits. At this point I got thoroughly confused so if someone who understands larger commercial systems (i.e. hospital size) could explain this I would be grateful.

Thanks for all replies

1) Pretty much yes, though overhead radiants can also be on VT. Normally CT used for things like fan convectors, heater batteries in air handling units etc.
2) Wonder what the intermittent VT circuit serves? Could there be some CT elements on it which need full temp part of the time? More details please?