Aqua Hot return air filter

[trower]

My 2014 Tour's Aqua Hot is great. But my DW wondered if there was a return air filter. I did some surfing and found nothing. Does anyone know if there is one and if not could one be retrofitted?

[creativepart]

RV heaters don't generally have return air systems. Some individual owners have created one and some manufacturers also have added filters to the heating ducts.

AquaHot in particular has "fuel filters" but not return air filters.

Amazon does sell a filter that can be inserted into floor registers:

https://www.amazon.com/gp/product/B000BWKMI2

[Wayne M]

I would be careful of adding any filter to a register, and especially return filters Registers and return filters are designed to provide the proper air flow to and from their desired application. Using a stronger (more fibers) than what the manufacture calls for can mean a resistance to the air.

I know there is a big market for this but if there are any AC technicians out there please chime in. I'll admit a mistake (never wrong.)

[Morich]

Depending on what purpose and how you might access things, the best option I think of would be bulk cut-to-fit air handler media:
https://www.amazon.com/Furnace-Handl.../dp/B07MVJSFP7

This is normally used in large air systems but might be easy enough to cut and put behind the air ducts where they are coming in and somewhat easy to reach.

Some shopping for amount and price as well as available might turn up something that seemed right. It comes in different colors, thickness, and width.
As a small point, it also works really well for fish tank filter media!
Which brings another thought that if you wanted to try it but not get into buying whole roll, you might shop fish supplies for "blue/white bonded media" to find a much smaller amount to test out.
https://www.amazon.com/Blue-White-Bo.../dp/B07RZMQSYS

[Wyatt]

Originally Posted by Wayne M

I would be careful of adding any filter to a register, and especially return filters Registers and return filters are designed to provide the proper air flow to and from their desired application. Using a stronger (more fibers) than what the manufacture calls for can mean a resistance to the air.

I know there is a big market for this but if there are any AC technicians out there please chime in. I'll admit a mistake (never wrong.)

No, you're right, so if you do add an air filter to your RV (like I did) that didn't have one, my recommendation would be to stay below a MERV rating of 8, and most importantly, change it often. I used a cheap MERV 3, just to catch hair, dust, and things since my register is near the floor.

[Wayne M]

My previous MH had a basement AC and the filter was something like 14 X 18 or whatever. I always used those green ones with the cardboard sides. Never had a problem with that AC for the 10 years we owned the coach.

Now with the present one there are ducts in the ceiling space evenly apart. Two rows. One for output, and one for return. Each of the returns have that little sponge like filter. Pull the vent off, remove the filter, wash it, dry it and put it back up. Works great. (just for info purposes.)

[creativepart]

The OP was asking about a return air filter in his AquaHot furnace... not an A/C system.

[Wyatt]

Originally Posted by creativepart

The OP was asking about a return air filter in his AquaHot furnace... not an A/C system.

Yeah, the AC filter is a different story. In ours, the AC filter is a worthless sponge like material, that like I’ve said before, is only good at stooping a small cat from being sucked up into the AC.

I’m ordered a custom electrostatic. It’s reusable, washable, as an upgrade to the AC, or furnace, In case you’re interested...

[trower]

Thanks everyone. I have not tried to access any of the aqua Hot return air ducts in my Tour but plan to investigate the idea of a filter of some type.

[Morich]

That is where I'm not seeing a good solution on most of your system when I look at the parts catalog. Assuming first that we are speaking the same with the air going to the heater as the return side?
On one of the three setups, I see three ducts/grills that I could see adding a filter under but it is on the side coming out, rather than the return side. But on the returns on all three, there seems to be no actual return plenum or line but just open fans which look much like small computer muffin fans with only a small, simple, wire guard. I'm not seeing an easy way short of building a frame of some sort, etc.

If you've not discovered this site, it can be a great tool for looking things over before trying to get to it. Kind of like "Superman" to see through walls?
https://catalog3d.winnebagoind.com/menu/Parts.htm

One might assume these units are in some form of compartment and it "might" be possible to build a grill to filter the air going to that compartment but, that's a pretty big guessing step!

[Wayne M]

My previous post regarding AC filters was to point out that changing a filter to a denser filter, or adding a filter to a non-existing filtered system, or placing a filter in the out-flow register can harm the system in the long run. SO, with the Aqua-Hot registers adding a filter could be detrimental to the system, and most likely could not be done to begin with.

There is no Hot air return in the Aqua-Hot system. I don't believe you can add one as it is a closed loop system. The Aqua-Hot sends the heated antifreeze and water solution through the loop, which returns the cooled solution to the Aqua-Hot’s boiler tank to be re-heated before being sent back through the loop again.

At each register is a Heat Exchanger and that is controlled also by the thermostat that turns on a fan in the exchanger. Adding a filter to the output of an exchanger can also hinder the operation of the fan.

I just have to ask why you wife is so adamant of a return air filter?


FYI: Service Manual

[Morich]

Originally Posted by Wayne M

My previous post regarding AC filters was to point out that changing a filter to a denser filter, or adding a filter to a non-existing filtered system, or placing a filter in the out-flow register can harm the system in the long run. SO, with the Aqua-Hot registers adding a filter could be detrimental to the system, and most likely could not be done to begin with.

There is no Hot air return in the Aqua-Hot system. I don't believe you can add one as it is a closed loop system. The Aqua-Hot sends the heated antifreeze and water solution through the loop, which returns the cooled solution to the Aqua-Hot’s boiler tank to be re-heated before being sent back through the loop again.

At each register is a Heat Exchanger and that is controlled also by the thermostat that turns on a fan in the exchanger. Adding a filter to the output of an exchanger can also hinder the operation of the fan.

I just have to ask why you wife is so adamant of a return air filter?


FYI: Service Manual

All very high class and upscale idea but still works the same as the old boiler systems that have been used for hundreds of years! Downsized and made portable but the theory is still just the same as most any heating system.
All it does is heat something, pass air over that heated item and use the warm air!
Whether it is a wood stove with a fan, a steam radiator, or a gas fired furnace, the idea is still the same.

[Wayne M]

Richard, absolutely - nothing really new about it. However there is no return air system. Heated solution circulates through the register and a fan sends it into the RV. Think the old house radiators standing along the walls. Nothing but heated water distributed by radiated heat and controlled by a valve that was opened or closed by hand.

Had a few of those in my days!

Aqua Hot does the same thing, just recirculates a heat liquid (hot water ) and the register acts as the radiator but has a fan behind it to help distribute the warm air. Not to sound redundant, but there is no "return air" system.

[Wyatt]

All good, but the idea of a filter is just to filter out SOME containments (in an RV). Anywhere where you can control the RETURN air, BEFORE going back through—or over the heating element/device, is prudent, so long, as I’ve stated the MERV is not too restrictive and limit the incoming air.

Adding a filter at the exhaust registers, is not providing the filtration one wants, it will serve only to restrict the outgoing flow.

[Morich]

Originally Posted by Wyatt

All good, but the idea of a filter is just to filter out SOME containments (in an RV). Anywhere where you can control the RETURN air, BEFORE going back through—or over the heating element/device, is prudent, so long, as I’ve stated the MERV is not too restrictive and limit the incoming air.

Adding a filter at the exhaust registers, is not providing the filtration one wants, it will serve only to restrict the outgoing flow.

Both the last two posts have some value and are true but then that is where we each have to figure out what we want most.

If we define return air as being a ductwork dedicated to the air going back into the heat exchanger, is it different than if we use a compartment that is used for storage to let the air return?

Anything that moves air out has to have a way to move air in, so if we call it return air or not is more a matter of how we define things.

And the issue of how much adding a filter changes the airflow is always going to be a thing to consider as we get the same effect when we deal with filters on any heat or AC. If we add filters and don't keep them clean, we reduce the airflow and get less value out of the system, even to the extent of over heating a furnace if it is gas fired.

But this system is not prone to overheating as the heated liquid is controlled by different thermostats and will just slow the liquid flow if the air is not flowing enough to cool it.

Since very few of us are going to say using an RV is ever going to be cost effective, it comes down to what level of comfort we want balanced against what level of efficient operation we require from the heating system.
And that comfort level has to also factor in how the wife feels about dust blowing around, doesn't it?
I'm not telling the OP to ignore his wife to get better operation out of the heating. That's his bear to wrestle!

[Wayne M]

There is no return air on the Aqua Hot system. It is a hydronic heating system that transfers heat to the heat exchanger which is then transferred to the selected zone. The hot liquid passes through the heat exchanger and a fan pushes the air into the zone.

The original poster asked about return air for the Aqua Hot. There isn't any return air in that system. It is a closed system.

[Wyatt]

Originally Posted by Wayne M

There is no return air on the Aqua Hot system. It is a hydronic heating system that transfers heat to the heat exchanger which is then transferred to the selected zone. The hot liquid passes through the heat exchanger and a fan pushes the air into the zone.

The original poster asked about return air for the Aqua Hot. There isn't any return air in that system. It is a closed system.

How does the incoming air get into or over the hydronic system? Isn’t that where a filter might be employed? Don’t know, just learning here about your system...

[trower]

Wayne, I was asking about filtering the air that passes thru the heat exchanger to limit the amount of particles blowing around the room. Sorry for the ambiguity.

[Morich]

The Aqua hot system is much like most of the heating systems we use in houses or RV in that the heat and the room air are not mixed but separate systems unless we are speaking of something like a fireplace where there is no separation.

The problem I see when looking at filtering the return is that it has no framework shown to attach any filter to it without building pretty much from scratch and it looks like it would be in places where it would not be practical to try that.

So looking at one of the three shows there is one which has grill/diffusers on the output side, so I would first look at those as the easier to design or figure how to fit a filter. One point on that is that it is often easier to keep a filter in place when it is blown against the grill rather than sucked away. But I'm not sure that is going to be good over the long term if you have to unscrew a bunch of screws to clean the filter!

We have a son-in-law who has massive problems with air quality and they use a portable air filter when traveling. Would something like that be easier to set up and still get the job done?

Lots of different options on that idea, if it might fit:
https://www.google.com/search?q=port...OABXifs-oB41qM

[trower]

We do use a room air filter as you suggest but when dry camping it would be nice to filter the air with the Aqua Hot. I have decided it is probably foolish to try to filter the air thru the Aqua Hot registers because of their design. Thanks ��