How To Optimize Taco RMB Settings

John_223

Yes, pump flow is fine and we did a heat loss to properly size the boiler, in fact it might be 1 size too large. I think the issues I've mentioned above can be solved by getting the right parameters in the RMB.

John_223

How To Optimize Taco RMB Settings

I have an in-concrete radiant system in a 1954 house with a Dunkirk condensing boiler and a Taco RMB with ODR for circulation. There are 8 loops and one zone. The RMB and boiler are installed with the correct piping and we are pumping away. I started with the following parameters in the RMB:
Design out 10
Design mix 95
Mix max 125
Mix min 80
Boiler 140
WWSD 70

At those parameter the RMB does not keep the house near the thermostat settings and drops about 5 to 6 degrees overnight and then tries to catch up during the day.

This is an install from last winter that went very wrong but should work fine with the RMB now intalled.

What parameters should I adjust and to what settings?

Should I even be running it on ODR or should it be on Delta T?

In spite of the boiler being set at 140 it rarely makes that temp. Is that a problem?

Thanks in advance for the help.
John

TimS

design mix too low ?

try design mix @ 120`

what was the problems before you installed the RMB?

EJ hoffman

did you do a heat loss?

are you sure of the head loss through the 1954 pipe is within range of the pump?

EJ hoffman

odr

Change your odr number up. more like 22.

Joe Mattiello

The 140 min temp setting is to protect the boiler if you’re using a boiler sensor on the boiler return, commonly used in a primary secondary piping arrangement. If you do not have a boiler sensor in place, or have a condensing boiler turn the boil min setting to OFF. The RMB might be minimizing the water into the radiant zone to allow the return water to the boiler to catch up. This should correct the problem for you. Let me know how it works out for you.

John_223

Yes the boiler sensor is in place. The boiler is a non-condensing Dunkirk so boiler protection is on. I've adjusted the design out up to 15 and the design mix up to 110 per the above suggestions. Our coldest day here in central Indiana is usually around zero. I hesitate to make big changes and I have let the system run for a day after changes. I just want to tweak it so the "flywheel" effect is minimized and so it stays comfortable overnight without running hard all day to catch up.

Any more suggestions would be appreciated.

Thanks for all the help.

EJ hoffman

If you did a heat loss,then you should

Have the numbers you need. Your design temp is the coldest day of the year. You said 0 for central Indiana then your design mix is Temp for your specific heat loss