Omnistat Thermostat wiring with 24VAC Transformer help

[sbex55]

I am working towards replacing my current thermostats with Omnistat2 units. I have a three zone baseboard hot water boiler as well as a separate single stage a/c unit. Both units use millivolt thermostats. I've determined I can use the RC-1000's but will need to add a 24VAC transformer to power each thermostat. In addition, I will need an HAI 29A00-1, Thermostat Isolation Module, for my main thermostat that operates the a/c and well as one heat zone. So far, so good (I think). 8)

Now my questions:

1 - Spec calls for a 24VAC 5-20VA transformer. Can I use a 24VAC 40VA transformer safely?

2 - Can I use one transformer to provide power to all the thermostats?

Thanks for the help!

Scott

 

[edselrt]

1.yes
2.yes

 

[sbex55]

1.yes
2.yes

Thank you! A follow-up question ... I only have 18/2 stranded wire available at the thermostat to provide power from the transformer. Is this acceptable?

 

[tmbrown97]

Don't see why not. Thermostat wire is solid 18/? - stranded will handle the same current.