Something I have never seen before

Good day all:

I arrived at an inspection and the client met me in the driveway.

Q Hi Doug Have you ever seen a furnace mounted on top of a water heater?

A Nope

Q Well… you are about to.


This it it.

After thinking about it for a while I deduced the unit on top of the water heater was actually an air handler. Heated water from the tank flows through the handler and a fan blows air across a coil to heat the air to heat the home.

I suspect the air handler also contains an A/C coil as well. The client needs to shut the valve allowing hot water into the unit in summer so the A/C will function.

Am I correct?

I did advise him to get detailed instructions from the seller prior to close.

Thanks for any




There are combo boiler system made to do just that. This however is a DIY unit that may not function as effeciently as a true unit. How effient is the waterheater? Is the water heater large enough to supply domestic hot water as well as space heating? Me thinks not.

Is the vent of the waterheater permited to be inside the duct system as it appears it might be in the photo? The potental for CO posinging rapididly moving throught the house with the aid of the air handler is not something I would want.:shock:

Did you open the access panel to see what the coil looked like? Would hope that he at least used a real coil instead of just some coiled up copper tubeing but it would’t surprise me.

I really like the expression on the guy’s (presumabley your client) face in the photo :slight_smile:

I suspect the air handler also contains an A/C coil as well. The client needs to shut the valve allowing hot water into the unit in summer so the A/C will function.

Am I correct?
Assuming that he is not replacing the unit then yes, that would seem like the thing to do.

And of course you got the dryer vert too right?:wink:

From what I see in the PIC, there is a water to air coil on the water heater and an ac DX coil on top of that. There is no valve manipulation required.

The ac coil should be downstream from the water coil.

It’s a combo or integrated unit…
I’ve only seen side by side, however, I guess “stacked” saves
twice the space.
There are many manufacturers, and a range of efficiencies depending
on fuel…

(Looks almost home made with that dryer duct connected to the air handler for those really cold/dirty laundry nights…;>)

Yes your on the right path, I have never seen the one pictured, but several of these types are on the market, normally in a condo style home. Did you get the make and model number

Paul…that’s a scary thought.

I would think it would HAVE to be electric…however Harry H/O can be
very creative with any energy source.

More picks-

Tank says its 95% efficient 34 gallon capacity

Small townhouse

Dryer vent?


Sorry guys- pick is not that clear

Dryer vent goes outside behind the unit.

Fuel is gas


Yes, Polaris 34gal 95% is a combo unit. Couldn’t get that info from the first pic

Thanks Paul!

Is there anything the client has to do when the warm weather arrives?

The heat side of the thermostat should be connected to a circulating pump. If its in off or cooling mode then the circulating pump should not be going thus no need real to close a valve. Any circulation movement from convection forces should be minimal. But as always, check with the manufacture for proper operating instructions

This file contains inspection information for these units which may be helpful to you.

I would also probably put a little more empahsis on periododic draining off of the sediment and other maintance than I normally would for a regular water heater. These ones are not only more $ to replace but if it goes you loose both your hot water and your space heating until its replaced.