Larger chiller-Venting into an A/C return Duct?

[acroholic]

I have a new chiller on the way (Tradewind 1/2HP in-line).

Venting: If the chiller vents into the room, then the return air duct picks it up at the return vents in the room. I have a return air duct running about a foot from the chiller. What is to stop me from venting with a motorized fan directly into the return duct, as the air would end up there anyways? This would be room air, same as any other air entering the returns in the room, except warmer. This would not be humid salt air from the sump area.

Opinions? Options?

 

[dannybradley]

What if you found a cabinet that can house the chiller and place it near, but not blocking the vent? You'd have to drill out the cabinet bottom and possibly install fans to feed the chiller with fresh air, but it would look better and be quieter.

I'd hate to see a duct running through my room.

 

[wbrown]

should be no problem with pulling the heated air from the chiller directly into the return.
You should not see efficiency gains, but no reason it won't work. If you wanted to make the chiller more effective, use supply air over the chiller unit to enhance the heat exchange. Heat given off into the room will have more time to dissipate and should not be as noticeable on the power bill.

 

[skriz]

You can vent it into the A/C system. Your efficiency of the home system will decrease since the air from the chiller is going to be quite warm.

 

[acroholic]

A picture is worth a 1000 words. Here are two shots of the cabinet, front and back. The tanks are just to the right of the recessed cabinet.

The back of the cabinet is framed into the wall, just 4 feet from my sump and all equipment. Just above the back of the cabinet is air return trunk line. I was going to tap into that, as it is about 2 feet away from the top of the cabinet, and install an in-line fan on the top to draw air from the chiller inside the cabinet into the air return trunk line.

I would either install a grille in one of the cabinet doors or drill some holes for air draw in the bottom of the cabinet so air can go up and out the top of the cabinet into the trunk return line.
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[acroholic]

Skriz;345818 wrote: You can vent it into the A/C system. Your efficiency of the home system will decrease since the air from the chiller is going to be quite warm.

Would it be any different if it is exhausted into the room and then enters the return or directly into the AC return line? I know it would be warmer directly into the return line, but that would make the room the reef is in that much cooler by the same amount, I would think, since that much heat is not re-entering the room.
Dave

 

[wbrown]

Acroholic;345823 wrote: A picture is worth a 1000 words. Here are two shots of the cabinet, front and back. The tanks are just to the right of the recessed cabinet.

The back of the cabinet is framed into the wall, just 4 feet from my sump and all equipment. Just above the back of the cabinet is air return trunk line. I was going to tap into that, as it is about 2 feet away from the top of the cabinet, and install an in-line fan on the top to draw air from the chiller inside the cabinet into the air return trunk line.

I would either install a grille in one of the cabinet doors or drill some holes for air draw in the bottom of the cabinet so air can go up and out the top of the cabinet into the trunk return line.

If you can walk up to the cabinet like that, a 4" duct should move enough air without a fan, of course more is better.. to a point. A good HVAC tech should be able to whip out his ductilator (conversion wheel) and tell you exactly how much airflow to expect from what size return.

 

[seedless reefer]

I would be worried about condensation.

The air that you will vent into the return air will be much warmer than the ambient air being pulled into the return from the room.

But then again, I worry about alot of things.

 

[enderg60]

All your going to do is make your home a/c run more. You will also want to keep an eye on it since even with an inline fan if the home system is not on the air may still get piled up in the system(think of the heat as a clog that can back out of the system)

As an alternative ducting it to an exhaust fan(like a bathroom fan) would more then pay for itself over a year or two. And putting it outside and running extra piping to it is the best option, just keep it out of the sun.

 

[acroholic]

EnderG60;345858 wrote: All your going to do is make your home a/c run more. You will also want to keep an eye on it since even with an inline fan if the home system is not on the air may still get piled up in the system(think of the heat as a clog that can back out of the system)

As an alternative ducting it to an exhaust fan(like a bathroom fan) would more then pay for itself over a year or two. And putting it outside and running extra piping to it is the best option, just keep it out of the sun.

I've thought about that as well, and that would eliminate heat from the house the AND the AC system, but it involves a lot of extra work. I'd have to drill thru the brickwork and remove a couple bricks. I can do it, it is just not easy.

Definitily agree, the best solution, however.

 

[grouper therapy]

Dave
I am just thinking out loud here but to make things more efficient I was thinking along the lines of moving the heat outside of the house like Ender suggested.
Ducting it into the return I think would do nothing for efficiency up or down .The heat is still in the house and has to be removed from the air entering the return. You compressor might have a harder time starting since you are super heating the coils and expanded the freon which puts more pressure on your compressor piston. If I did choose the direct return approach I would most definitly put a hard start kit on the unit.

 

[grouper therapy]

ares;345912 wrote: its all a closed loop, venting it to the room will eventually get sucked into a vent, itll warm up the room, but the room should dilute it enough to not be an issue for temps, but the small amount will make the AC work a touch more.

on the flip side, right into the vent, and it instead makes the AC work harder when its on, but the room wont be affected. 6 of 1 half dozen of the other IMO. (<u>though what happens when the AC is off?)</u>

<u>I wouldnt vent it outside, reason being is that any air you blow outside means air being sucked in somewhere.</u> and Id venture to say Id rather recirculate the hot dry air of the chiller vs sucking in hot humid air from outside.

That was might thought with the heating of the coils when the ac is not running then it trys to kickk on with the super heated coils

I would set the chiller outside or in the basement somewhere out of the closed dloop circulation and just pipe the water to and fro

 

[grouper therapy]

Dave
I think Joe (Sailfish) has his chiller under his house might want to hit him up for an opinion. Congrats by the way<span style="color: red"> totm</span>

 

[wbrown]

could always run a sump system, cool the sump water, and pump that to the DT's sump...
More complicated, but isolates the high head pressure going through the chiller.
How much heat load can a chiller really put out? If the main house A/C is already running, you only are looking to remove heat from MH's and pumps right? Not as if the chiller will be running full bore 24/7.
Based on that, I'd say whatever you put directly into the house return is going to be nominal, and if it only draws air while the house unit is on, where's this saturation going to come from?

 

[grouper therapy]

The chiller would not have high head pressures if you were pulling from and returning to the same source. Closed loops do not have hardly any head pressure mainly just static pressure. A 1/2 hp chiller is around 6000 btu's which is alot of heat being sent somewhere. The heat does not disappear it is simply removed and placed elsewhere.

 

[wbrown]

what's a reasonable estimation of heat exchange? 50%?
Titanium is not the most efficient of heat conductors, but is likely the best choice for the environment we want to use it in.
I'm asking for my own knowledge, not to inflame the discussion.
Has anyone measured the output/outflow temp from a chiller lately? I'm curious what efficiency there is, and if it might be improved.

 

[acroholic]

I run the fan on my HVAC continuously, so my air returns are always pulling in air, regardless of the AC being on or not. I think the net effect of piping directly into the return duct is a redistribution of the heat throughout the house, which will make the thermostat turn on a bit quicker. AFAIK, it is only the thermostat that turns on/off the AC.

Remote locating the chiller is not really an option for me, and I think that would overly complicate the setup. My plan for water movement is to use a Mag 12 in the sump intake section run water to the chiller, then back to the return section.

It is only a 12 foot run to vent directly to the outside. It is only two feet to vent into the return duct.

The chiller is going into the cabinet. I guess I can always decide on venting options later.

 

[wbrown]

Do you happen to have a thermometer to place in the exhaust air from the chiller? a way to measure ambient air would be good info to have as well, but a reading from the thermostat of the house would do for grinz.
Contact time is everything in a heat exchanger, the more contact you have between the component to be cooled has with the component doing the cooling, the more efficient the system will be.

 

[acroholic]

ares;345988 wrote: Dave, is your cabinet vented at all now? its was under the tank, that cabinet wasnt sealed was it? perhaps explain why the chiller wasnt keeping up.

My chiller wasn't keeping up because it is only a 1/4 HP. I have 300 gallons net in my system now. I bought this chiller when I had 150 net gallons (120 gallon tank and sump only). I have since gone to a 210, 100 and 35 gallon all in one system It is in my modern series stand, which is open back, and I have a high flow fan blowing air out the back of the stand. It is pretty well ventilated.

Too much to ask this small a chiller to cool that high a volume. The baseent location helps keep the system cool a bit, but I have 1850 watts of halide light over my reef tanks, not including the 750 watts of halide over my 265 gallon FW planted tank.

My current 1/4 HP chiller hasn't worked at all during the winter, and it is only coming on a bit now with the current cool temps, but I got a taste of what is to come later this summer last week when it hit the 80s.

 

[grouper therapy]

I'm with you now Dave. With you running the fan 24/7 that would cancell my (theory) of super heating the coils. By exhausting into the continuos running fan you are distributing the heat thru out the house and not super heating one room. I don't know if that would make any difference in efficiency but would surely keep that room cooler!!
I wish I knew a mechanical engineer!!! ENDER ENDER CALLING ENDER