Suggestions for Taco RMB Set-Up

Jim_64

I have recently had Taco RMB installed and need advice on setting the parameters and proper electrical connection to the boiler.
The boiler is a Dunkirk, noncondensing Plymouth Extreme with a Honeywell L7148F aquastat controller. It has one zone 1950's in-floor concrete with a 50K load. The mechanical contractor did a very nice job of correctly piping in the RMB and correcting all the mistakes made by the previous installer.

Since the boiler requires a minimum boiler return temperature the 2 RMB sensors are installed on the boiler return and the radiant supply. The outdoor sensor is also installed.

What would you recommend the following settings be:

Outdoor Design Temp

Mixing Design Temp

Mixing Maximum Temp

Mixing Minimum Temp

Boiler Minimum Temp

And Boiler Aquastat Temp

The heat demand is wired into the RMB but the but the boiler is NOT connected to the 2 pin terminal block. Should this be connected and if so where does it connect on the boiler?

The way the RMB is currently set up the house gets cold and then overshoots the thermostat temperature.

I've attached 2 photos taken before sensor installation but I'm sure they are in the right location. I think I've got the only RMB in Indiana and the local distributor has not returned my calls.

Jed_2

Piping

See attached and compare.

Jed

Jim_64

Thanks. That solves the wiring questions. That diagram was not in the RMB installation instructions that came in the box. Now if someone could please help with the settings.

Joe Mattiello

The outdoor design temperature should be the average coldest day. That information can be found in an almanac, or chamber of commerce. The Mix design temperature should be set using the outdoor reset curve on page 6 of 16 in the RMB instruction book. Normally, it's set to the highest water temperature allowed at the outdoor design average coldest day setting. Mix Max, is the hottest water allowed into the radiant system without detriment to sensitive components, like cement, or wood floors, etc.. Minimum is not always necessary unless the application is floor warming. You can simply set it to off. Boiler Min is only required when you are using a boiler sensor, and boiler protection is the objective. If not turn it off. This is where so many of my calls come from. Contractors/homeowners will enter a 140 degree min temp, with out using a boiler sensor, and they will see a boil open error message. The boiler aquastat temperature is your high limit dictated by you, and normally set to 180 degrees. Hopefully this helps you. Additional information on the RMB, and other Taco products is available on line at www.taco-hvac.com. For your reference I attached a technical document PA09 on the RMB

Joe Mattiello
Technical Support Engineer