Question: The purpose of actuators on heating pipework.

[The Bedwetter]

I am currently installing four radiators as a favour for a friend in an office building of 3 floors – the rads are required on the ground floor. The heat for the building comes from three boilers connected in series. (All hot water is provided by several multipoint water heaters). Three branches of pipework run to each floor from the boiler-room (on the top floor) and each has what I understand to be an ‘acctuator’ connected. The two actuators connected to the ground and top floor are fixed in the OPEN position and are not affected whether the boilers are switched on or off - I can see no purpose to their installation.

The actuator for the 1[SUP]st[/SUP] floor, on the other hand, switches to the closed position when the boilers are turned off. I am confused as to why only one of the actuators operates. Also the operating actuator looks to be out of alignment in the open position. Additionally, because this actuator closes when the system is switched off prevents the 1[SUP]st[/SUP] floor supply from being drained.

I would very much appreciate understanding the purpose of the actuators. Thanks for any help.

Please note that it is the orange actuator that serves the first floor.

 

[snowhead]

They're Zone valve Actuators controlled by thermostats or sensors on each floor.

Re the Orange one;

It needs a supporting bracket at the bottom, it's twisting when it operates.
They look like Belimo, if so there should be a slot in the case at bottom which clips into a pin on a bracket.
It should be vertical.

As for why the others are fixed, I'd guess they've failed and not been replaced.

To drain, remove the actuator and turn the valve open.

 

[The Bedwetter]

OK I see what you mean. They are a bit like motorised valves in a conventional domestic setup, then? Yes, it is a Belimo AF230-S.

Sorry, but how do you remove the actuator and turn the valve open? Is a tool required or can it lust be lifted off?

So if the two have failed is this likely to have impact on the operation of the system overall making the boilers work harder making the system less efficient?

 

[lame plumber]

out of interest, do you have a plumbing background, just asking?

 

[snowhead]

There's a screw down the middle of the handle.

Assuming the rads have TRVs there won't be much loss with the valve open.

 

[Dotty]

They're actuators designed to give modulated temp water on the heating circuits dependant on outside air temp and occupancy. They mix the return water with the flow as necessary.

I assume that you have had little dealings with commercial installations.

 

[lame plumber]

I would assume your assumption to be a very poor one John, based on his original questions

 

[The Bedwetter]

home plumber: see below.

snowhead: Yes, just about all of the rads in the building (around 30) have TRVs.

croppie: Right, I onderstand their purpose, Thanks for this. But, to you (and hp) I have not come across this sort of thing before as I simply do not cover the commercial area. The difficulty here is that the landlord of the building is responsible for the boilers, pump, pressurisation/diaphragm stuff but the several occupying leaseholders (which are all charities) are responsible for their own radiators and pipework. So having been asked to replace some rads I am inevitably drawn into rather unknown territory. No worries, I am not going to risk a lawsuit by tampering with components for which I have no authority (or experience) but I was simply determining whether said landlord should be brought up to speed with the seemingly non-operational stuff in the boiler-room.

Thanks, guys.

 

[Worcester]

Blending / mixing valves like these (or similar) are common on domestic underfloor heating systems and domestic biomass systems.

We've got one domestic property where we're installing 4 circuits, 2 blended weather compensated (rads up/down), one blended fixed flow temp (towel rails), one non blended (DHW cylinder)

With the drive for energy efficiency, you'll start to see more and more of this in (larger) domestic properties.