Commercial heating - baffled by this one

[Marty92]

Hi all,

I am contracted to replace a control system for a commercial heating system, it's packed up following the removal of two older boilers, replaced by one w200.

The boiler swap was all very dodgy - I given up asking questions!

I am some what confused by the original intended design.

There are 7 zones which are a mixture of rads and UFH.

4 of said zones have satchwell csc's and Svt's

The csc's control satchwell arx1202's / mbx4451 valve bodies

The valves are positioned in the returns just prior to the return header, the centre port is connected from the flow header via a bypass valve in the direction of standard flow.

Essentially they are connected as diverting valves.

given that I have OS temps and the system seems to be designed for weather compensation how can this work?

I cannot see any means of limiting flow water temperature or any way of differentiating temperatures between zones.

What am I missing?

thanks

martyn

 

[oz-plumber]

A couple of Photo's may help.

 

[Ermintrude]

Boiler not modulate down in linear response to weather comp? All valves doing is bypassing circ. ufh should have own temp regulator?

 

[Marty92]

Thank for the responses.

No weather comp on boiler, No os temp to it.

The outside temperature sensors (4) were wired to the Satchwell CSC compensators and the valves driven from the CSC's

No other controls on the Ufh.

Primary pumped header has a user set stat but that would limit every zone so no good.

The valve is a bypass at the moment but that makes no sense, why compensate a bypass valve & why no modulation for temperature?

 

[Marty92]

1 csc controlled valve
2 bypass
3 return header
4 take off for centre port on valve

 

[wetdrip]

Boiler not modulate down in linear response to weather comp? All valves doing is bypassing circ. ufh should have own temp regulator?

How do you modulate down ermi?

 

[Marty92]

I assumed he was referring to a linear graph based on the Heizkurve.

that would require the boiler to have an external temp sensor - it doesn't

 

[Ermintrude]

Looks aright dogs dinner. Pump covers off insulation missing. Typical mess. Who fitted boiler ? How did it meet part L

 

[Ermintrude]

Csc set for each zone. Basically they control zone temp ..... When it's hot enough brings in return water keeps running till stat in room satisfied? What sort of control u want to install?

Weather comp drops the csc target temp or lifts it but keeps DHW circ at a constant.

 

[Marty92]

The guy who "fitted" the boiler has gone MIA, he was GSR but it has lapsed according to the hrs it was not a reg'd installation - no surprises there!

I assume he removed the insulation for access as there is a pile of it to one side.

I have all the pump covers off as it's currently be totally rewired...

I'm very happy to admit I'm ****e at replacing that type of insulation so looking for offers

I'm only really contracted to do the controls, but they are a good client and I'd like to be satisfied with the whole thing on completion - bar ripping it all out!

 

[Marty92]

But there is no route for the return water to be recirculated it goes back to the boiler...

 

[Marty92]

New control system work in progress ...

 

[Marty92]

No dhw from boiler

 

[Ermintrude]

Someone reversed flow and return ? Sure csc supposed to be on the flow and have a return into center? Sketch out pump location ?

 

[Ermintrude]

New control system work in progress ...

Can't u just use a Honeywell wiring center and a wireless stat?

 

[Ermintrude]

Pipe work schematic for one csc zone might be a bit easier to see

 

[Marty92]

Can't u just use a Honeywell wiring center and a wireless stat?

Did you see the photo of the new control system?

 

[Marty92]

That drawing is basically it but the pump is in the flow AFTER the tee off to the valve...

 

[Ermintrude]

 

[Ermintrude]

Re orient valve so

 

[Marty92]

Ha, thanks for that, the "what I should have" is what I originally thought, but this system is weird!

The only answer I have at the moment is it must be running flow control... CV maybe?

 

[Ermintrude]

Were all unions old and in disturbed? Previous plumber re jig? Just there is a bit of black on side of one barrel and the top is bit that usually gets missed when red oxide in situ?

 

[Marty92]

I had wondered that and your red oxide is a good spot, but what about the bypass valve that appears undisturbed and is in the standard flow direction?

fancy a trip to the big smoke?

 

[Ermintrude]

All the clunge in hull wouldn't get me missing my sons 3rd birthday. Plus packed out till November. Taking on staff.

 

[Marty92]

I know what you mean! Never been so busy!

presumably this valve would need turning too

?