Buck Boost Transformers

Big Will

I need 250 VA at 24 volts. I want to isolate each zone thermostat, valve, and relay with fuses but use one large transformer. I see Buck boost transformers that fit the va output with the primary voltage at 120. But the definition of a buck boost is to raise or lower the voltage up to 27%. (from Wikipedia).

I have seen large enclosed wall mount 24 volt transformers and worked with them before. I have never had to order them and cant find any thing that fits the bill that is not called a buck boost transformer.

Barbarossa

24 Vac

A 120 to 24 VAC advertised as a buck boost can be used as a 24V isolation transformer it all depends on the arrangement of the leads. You can also look at Square D and others vendors under control transformers. Remember these are not self limiting transformers common to HVAC so the NEC rules apply as to primary and secondary fusing and wether you choose to ground the secondary X2. At this point it is all about local code.

Jim Davis_3

Dongan Transformers makes what you are looking for. They have a Series 50 Transformer that goes up to 1000 VA, 120X240 - 24 volt units.

Larry C_13

What is in a name?

Try looking for "Control Transformers" and "Buck / Boost Transformers".

Like the other poster said, the NEC applies whenyou are working with non Limited Power transformers. Work with a local Electrician and inspector to make sure you don't inadvertantly create a problem by making the system more robust.

Another choice would be to use individual transformers for each zone.

Good Luck.

Larry C