Adding a water to air exchanger.

BWBays

I have a one zone, one circulator and one thermostat in floor system for a small living portion of a pole barn home. It has served me well. I have decided to add a water to air exchanger to the shop portion of the pole barn home. (I know at the time I poured the Crete I should have put pex on the shop side but at time I didn't know I was going to get free gas.) I would like to run them off one circulator, two zone valves with two thermostats. How can I get the fan for the air circulator and pump to come on at the same time as the shop zone valve opens when that thermostat calls for heat? I am working with a zvc406 controller.

Jamie Hall

The zone valves would be controlled by the thermostats, and when either one opens use the end switch on the zone valve to turn on the circulator and the boiler. You could also turn on the air handler fan at the same time, or you could get slightly fancier and have the fan be controlled by a strap on aquastat on the feed line to the air handler.

EdTheHeaterMan

What zone valve are you using? I assume you already own the ZVC406, otherwise you are purchasing too much control for what you want to do.

Easy peazy to do this. Does the water to air heat exchanger have a fan built in, or are you putting pieces together that you already have. If it is a pre-fab air handler with a fan and a coil, then what is the model number?

With all this information I can draw you a simple wiring diagram that will make sure that the Shop duct fan does not blow cold air when the thermostat calls for heat until the duct coil is hot. and that itr does not blow cold air after the call for heat is completed but the coil water temperature sensor is still hot while the water in the coil has cooled down. I have done this several times for customers and it is easy to do.

EdTheHeaterMan

After looking at what you want to do, and not knowing what type of heater is currently heating your radiant floor heat tubing, I realized that the floor water temperature should not go much above 115° and should probably be lower. Also the air handler will need 160° to 180° water in order the heat the shop area with a duct coil or water to air heat exchanger. With the need for 2 water temperatures you will need a mixing valve of some sort (to stay on the simple side of things) and a low temperature zone circulator pump. I have a diagram of what it might look like.

This is just a guess based on the limited information provided. The type of boiler or other heat source may change the design. Also, the insistence of using a Taco ZVC 406 will require the addition of a RIB U1C relay to operate the Low temperature zone. The high temperature zone can use a zone valve and a strap on aquastat (like a L6006C) to operate the fan in the duct system

This is not the best design. I may use a different control system and separate zone pumps. but based on the information at hand this will work.

So you need to get a pump, a zone valve, an strap on aquastat, and a relay in addition to the heat exchanger and fan and duct work, if any.

hot_rod

You can get coils sized to low supply temperatures120 or lower is possible

hot_rod

Jaga makes fan coils that can operate at radiant temperatures, to supplement floor radiant for example

BWBays

I have a rudd ultra series condensing boiler, 007-f5-71fc pump currently. With a sr501 controller. I put together a 20x20 exchanger with a 20" attic exhaust fan that pushes 3300cfm. Two 2 wire valves and the zv 406.

BWBays

Ps I run my floor water at 180. It thottles down for the pottable hot water. 

BWBays

One more thing, the boiler provides the potable on demand water at about 110. 

pecmsg

BWBays said:

Ps I run my floor water at 180. It thottles down for the pottable hot water. 

WHAT?

GroundUp

The ZVC406 wiring diagram is very clear on how to do this. With that said, a concrete radiant floor system should NEVER have a water temp over 120. 100 is even better. A typical forced air system will want a considerably higher temp, but if your BTU load is low enough it may be viable to use the low temp water for both zones. Turn that slab temp down immediately.

BWBays

It has on demand water built in to the boiler. When any faucet is turned on the boiler automatically turns off the floor heat and switches to on demand pottable at 120 degrees. Once the on demand water is no longer needed it throttles back up to the 180 degree radiant floor heat and turns the circulator pump back on.

BWBays

I'll turn it down but it has run this way for 2 years now with no problems. I have the pex poured in 6-in concrete

BWBays

I just looked at the temperature gauge of the water going into the floor. It's at 120°

hot_rod

BWBays said:

I just looked at the temperature gauge of the water going into the floor. It's at 120°

That sounds better.

You can size a coil to 120 supply. It would be helpful to know how many BTUs you are trying to move from the coil.

You can buy or build a fan coil.
Farmers around me would use a truck radiator with a box fan hung behind it

BWBays

I bought a 20"x20" heating coil backed by a 20"x20" fan that can push 3300 cfm. I'm just trying to keep a 30x30x12 ft ceilings at about 40 degrees during winter in Ohio.

BWBays

The heating coil is rated at 160000 btus. 

hot_rod

That should work. If it has or you can add a variable speed function to the fan, that will also help adjust the temperature coming off the coil.

EdTheHeaterMan

I am wondering how the 180° from the boiler gets to 120° at the radiant floor tubing. I can see using one circulator at the mixing valve MIX port and the boiler feeding 180 to that mixing valve HOT port and the return to the boiler passing by a Tee fitting to the COLD port of the mix valve.

I don't see how that 180° boiler water will get to the 20x20 fan coil. i can only see getting the 120° water getting to anything in that system. If you believe that 120° water in the 20x20 coil will do the job then here is the diagram I would use.



I believe that there is a boiler pump built into the Ruud Combi and the External Taco 007 F5 is the Space Heating Pump, and it can be connected to the boiler to operate when any zone valve opens.

I believe that you have a SR501 that you don't need, if you connect the space heating pump to the boiler control panel. That means you can use the SR501 to operate the fan motor for the space heating coil, and the use 5 and 6NO to operate the zone valve

I added a file below so you can zoom in to see the details on the piping and wiring diagram.

Any questions feel free to PM me.