Hydro Air Help

MichaelinSalem

Hey everyone,

Here's whats going on, I'll try to describe it the best I can.

we recently had a hydroair system attached to a Navien tankless hot water heater. The heat does no work very well. If the temp is set to 80, the house will get to 65, on a good day, if we're lucky.

The air flow from the vents is very weak, and the air is not warm. The plumber and HVAC guy are in disagreement about whose fault it is, and whats wrong with the system. I'll detail what they think, but I'm wondering if we can get any other opinions.

HVAC guy says the Navien is installed too far from the air pump (it's about 6 feet away) and that the plumbing lines are reversed meaning instead of heat being pumped in, the cold is being pumped out. He also says the air pump has only one fan speed.

The plumber says it doesn't matter which way the lines are installed (which to me doesnt sound right, but I'm not a plumber)

thankful to anyone who can help.

EBEBRATT-Ed

If that's what they told you neither one knows what they are doing.

There is an in and out for the air handler piping. It probably won't make a huge difference but it should have been done right.

The piping should be piped so the water going into the coil is moving counterflow to the air flow. Post a picture of the ahu piping connections and we may be able to tell, The connections are usually offset vertically from one another.

The air handler within 6' of the boiler is fine.


Sounds like no coordination between the two installers.

We need pictures of the install and more information

Are you using a water heaater to heat your house? Where are you located?

EdTheHeaterMan

Can you give pictures and a model number of the fan unit and the Navian?

If it is a water heater only you have the wrong boiler. Pumps can pump in or out of a boiler. Water pressure & temperature drop across the fan coil, water temperature, airflow, and water flow are all important to resolve your problem..

GW

Wow 🤩 just let them duke it out. The hvac guy can’t increase the blower speed? Then the ducting is too small, he chose the wrong equipment, he’s utterly incompetent, or all of the above. Are these moonlighters you hired?

The plumber appears to have more of a clue. What’s the water temperature? Water direction is minimal. Heat will jump off the train regardless of the direction of the water. 

HVACNUT

If the Navien is strictly a water heater and not a combi, then I agree with @EdTheHeaterMan. Wrong equipment. If it is a combi, Navien has a diagram specifically for hydro coil applications using hydraulic seperation. They offer their pre piped manifold, or the installer can build their own.

MichaelinSalem

Hey guys thanks for the responses. The plumber is new and was more expensive than some other quotes lol( but thanks for that judgement ) he came as recommendation from a contractor i work with, the HVAC guy I’ve used a few times on other projects. 

MichaelinSalem

Oh and the return duct was taken off to see if that would increase volume to the vents. It made no difference. They’re ripping out the current duct work and replacing with larger 

GW

Find the manual for that air handler and snap a picture of the wiring diagram. Should not be very difficult to find. I don’t work with that model, but I’ll fall off my chair if that blower motor does not have different speeds. 

Jon_blaney

Three speed motor.

Jon_blaney

Check this was done. "Tankless Water Heater applications: For Tankless Water Heater applications, install the optional high capacity flow control module (#940-2CV) in the piping between the Tankless Water Heater and the HBXB-HW air handler."

EBEBRATT-Ed

Well, it's piped in PVC so your working with limited water temperature probably 130ish maximum. Probably why the connections to the coil are so large.

Show some more piping pictures. You have 1/2" or 3/4" coming off the water heater looks lie 2" at the AHU. The pipe without the circulator is supposed to be the hot water inlet and should be the supply from the boiler