Hydro Air with a Variable Speed Air Handler

Kal Row

he can plug in an AM4 module into the ultra, and modulate it externaly - like us hard core tekmar folks do - i wish there was an independant test of a pair's of ultra's controled by either WM's own MBS system, or externaly modulated by a tekmar 265 or (ahem) heat-timer's

Trevor Baptista

Is this a good match?

I am using a Trane VS air handeler with a "comfort system" T-Stat. There is a hydro coil for heat in the AH which gets its heat from a WM Ultra boiler. I keep hearing that VS air handlers are not good with a boiler that uses a outdoor temperature reset. Please help clear the air.

Trevor

TJ_3

I've been running two variable speed AH off of one WM Ultra 105 for two years. I am using the OD reset that comes with the boiler, but the AH are run thru a Tecmar OD reset panel that also handles my indirect water heater and an injection setup for my radiant. The way that I handle it is to use two stage stats with 1st stage of heat calling for the very low speed of the air handler so that when the temps are mild and the water temp is low the AH runs on such a low speed that the dischage temps are ok. And when the oudoor temps are low and I need more heat the 2nd stage of the stat kicks in runs the AH on a higher speed and of course the water temps are higher because of rest and again the AH discharge temps are just fine

Trevor Baptista

Cool,

Right now I have no idea what tells the AH what speed to blow at. However, I do believe the T-stat is controling that. It seems the higher the target room temperature is on the T-stat from the actul room temperature the stronger it blows. For example if the room is at 68 and I set it to 68 then when it cycles, the air flow is super low. If the room was 68 and I set the T-stat to 70 then the air flow is like a hurricane. It is pretty wild.

John Starcher_4

Not sure about other manufacturers.....

...but on the American Standard or Trane VS air handler, you program your fan speeds for 1st and 2nd stage heat. The thermostat would dictate which stage "mode" the ahu would be in, and the corresponding fan speed would occur.

Starch

Mike T., Swampeast MO

I'm quite certain that it's a vector-driven thermostat, so yes, the further the current temp is away from the setpoint, the greater the airflow. The same thermostat also controls their "modulating" (actually highly staged) furnace.

Not sure how you can integrate this with an Ultra as I rather doubt that the air handler/thermostat and the boiler speak the same control language.

The possibility is there for very effective control. Talk with both Trane and W/M to see if they know of anything that allows their thermostat to "talk" to the boiler in some way or other...

Trevor Baptista

I think it is OK the way it is. I like the fact that the air flow is based on the indoor temp and the water temp is based on the outdoor temp. Does this make sense?

Kal Row

the ultra is good with any load by virtue..

of the fact that it modulates itself to the load, it uses outdoor resets one of the hints to control the rate at which it matches the heat loss - so don’t worry about it - just treat it as efficient hydronic heat source black box!!! - Other than guaranteeing good flow through the boiler , and not filling it with very acidic or very alkaline water, there is very little you can do to screw up the ultra

Sal Brunetto

re:

Teh WM Ultra will modulate to the coils need for heat as applicable. The outdoor temp sensor just gives the control module another parameter to "plug" into its energy saving algorithm.

Sal Brunetto
Weil-McLain