Circ pump, spirovent, and motorized ball valve location causing potential air intrusion

[hartkem]

My EKO 40 is in a small 10x12 outbuilding feeding my 500 gallon storage tank in my basement. I also have another line from the boiler going to my shop. In my shop is a forced air furnace with a WAHX installed. I've noticed my spirovent dripping water and removing air. I actually have three spirovents in the system. One at the boiler, in the shop and in my basement. The only one doing this is the one in the shop. The shop is located uphill from the house and boiler. Approximately 10' elevation change. Water pressure is 15 at boiler and slightly more in the basement where the make up water is. I think my problem is how I installed the circulator in relation to the motorized ball valve and spirovent. The pump is actuated off the contacts in the motorized ball/zone valve. I am pumping away from the spirivent which I think is causing low pressure especially when the valve closes slightly before the pump shuts off. The gauge pictured is attached to bottom of spirivent and is about six pounds when system is on. The gauges drops to zero when shut off. If I close the valve between the pump and spirovent the gauges reads 10.

 

[maple1]

I don't have a spiro vent - does it have a bleeder type cap on the top where it vents? That can be kept tight?

My vents do - like a valve stem cap. I usually keep them tight, and unscrew once in a while to see if they've accumulated any air underneath.

Sounds to me though that you have an accurate diagnosis.

 

[leon]

Where is your expansion tank?

With your circulator where it is it is causing issues with vacuum. Do you really need the solenoid valve? you could move the spirovent to the location of the solenoid valve and just wire the circulator with out it.

 

[Bob Rohr]

Looks like that Taco is pumping away from the coil and Spiro vent, zone valve is on the supply?

Vents do leak from time to time, you can screw a 1/2 cap on the Spriovents to cap it off, but then of course it cannot remove air.

Typically on central air vent back at the boiler is sufficient, maybe a small float type vent at the AH or high points.

 

[hartkem]

My expansion tank is in the basement where my storage is. Yes, I am pumping away from the coil and vent. It only leaks after some air is purged and then it stops after a bit. The motorized valve is there to prevent flow through this circuit when I'm not in he shop. I'm teed in at the boiler. Maybe I don't need it?

 

[leon]

Your current circulator or "a" circulator needs to be ahead of your air scoop or steel expansion tank to
create the point of no pressure change. you can cap off the spirovent and see how the system responds
and just let it go until summer when you are not burning wood to move it.

 

[Bob Rohr]

The air scoop should be at the hottest point in the system, right at the boiler. The expansion tank establishes the point of no pressure change, with circulators in multiple locations that gets a bit awkward.

As long as you have pressure on the gauge at the coil when it is running, you are not creating a sub atmospheric condition, and air should not, cannot enter with pressure in the system.

 

[velvetfoot]

On the other hand, the spirovent in the shop is at the highest point in the system, just acting as an air vent at that point, and perhaps the system hasn't been running that much this winter and some air accumulates?

 

[hartkem]

It is the highest point in the system. I've had this system for 4 years now and this happens every year. I think the problem is that the zone valve closes and then shuts off the pump with the end switch But as the circulator is slowing down the zone valve is already closed and it lowers the pressure between the zone valve and the pump where the spirovent is located. As others have said I think I need to pump towards the spirovent and not away. Not sure if the spirovent and zone valve should change position or just move the circulator to the supply side.

 

[Bob Rohr]

The end switch on that valve breaks open within seconds of the heat call going away, then about 5-7 seconds for the valve to spring close and seal. I suspect the pump, in fluid stops spinning almost instantly.

I'm not clear on why a pump and a zone valve? A pump with an integral check would prevent ghost flow.

Circulators can pump towards or away from that purger without a problem.

Unless that gauge drops to 0 or lower when the pump is running you are not pulling a sub atmospheric condition and air will not enter. To prove that buy a 1/2 cap and screw it on the discharge of the Spirovent.

Most common is a pump, and a float type air vent on a tee at the return side of the coil, make it the high point to catch any air that migrates to the coil.

High point, float type air vents are found on air handlers, radiators, radiant manifolds and on top of most cast iron boilers.

That Sprio can actually hold a small amount of air, until enough of a bubble causes the float inside to drop far enough and spit the air out. It may well be holding not expelling your rouge air bubble, and it is not at the high point at the coil, near the zone valve.

Get rid of the zone valve, make that ell a tee and add a float vent there, that should solve your problems once and for all.