zone valve & burnham

realolman

I don't get. They're supposed to draw .9 amps each 3 X .9
X 24 = 64VA... although you are right... they say you can run 3 of them on a 40VA transformer.

I know that they contain a switch that turns the heater which operates them on and off as long as the thermostat calls for heat. That's the only reason I can think of that would allow them to run 3 from a 40 VA transformer, and I don't see how that's kosher even with that.

[Deleted User]

Zone valves and Burnham

Burnham gas series 2intermittant ignition.Two taco zone valves do I need a separate 24v transformer for the zone valves.Boiler trans is 50 va.
Thanks Mike

JackR

Zone valves

You are fine running two zones valves off of the 50VA transformer that comer with the boiler.

Joe Mattiello

The 50va transformer has enough VA to handle the additional load of 2 Taco zonevalves. Taco advocates 3 zonevalve per 1, 40va transformer. Hopefully this helps

Unknown

The way that works

is that Class II standard DC20-92 transformers can operate at 200% of capacity that says that a 40 VA can handle as much as an 80 VA demand with very little loss of voltage. All heating and cooling equipment from the factory must have that class of transformer. That is why it is important to use good transfomers when replacing them on a job.

madman

zone valves and burnham

I would beg to differ, you will end up burning up the transformer, with the burnham you will need an additional transformer. the unit was designed such that the transformer is sized for the load of the boilers control cuirits not the additional load of your zone valves, I am positive that you will recive the same responce from Glenn @ Burnham.

MIKE6

2 taco zv + burnham = smoke

I installed a separate trans per my boss and smoked the boiler transformer.Do i need an isolation relay?The trans were both 50va and wired the two hot 24v lines together to phase them.

madman

Pull out your manual and go to page 17, it covers the wiring of zone valves, if you can not find the manual it is online at their web site

madman

Mike go to your series 2B Manual pg 17 it is all layed out for you there.

realolman

well ...


Are you sure it is National electrical code compliant to load it to twice it's rating? Why is it rated at 40 VA ?

Unknown

If you are

interested I will send you the white paper on transformers concerning NEMA (National Electrical Manufacturers Association) standard DC 20-92. It perfectly all right to use transformers in this manner, however bigger is always better so if it is a concern use and 80 VA.

You can also parallel connect two 40 VA transformers just make sure they are in phase.

realolman

I'd like that

very much... thank you. Can you send it to my email address?

I just installed 3 taco zone valves and I did in fact buy a Honeywell AT175A 75VA transformer. It says it is a class 2 transformer and is fused internally.

So 75 VA / 24 = 3.125 A., but you're saying that it will supply 6.25 without blowing the fuse, and that it is NEC code compliant to load it to twice it's listed rating?