New hot dawg heater--too loud!

[onebadbowtie86]

This winter I decided to replace my 30 year old reznor hanging garage heater, In hind sight I should have left it in as it was running fine and was nice and quiet, but had a small crack in one of the heat exchangers.

My buddy has his own heating/cooling business and recommended the cayenne 75k garage heater by adp. We ended up putting 2 of them in but both rattled pretty bad on cool down due to loose fitting baffles in the heat exchanger. This heater's fan was nice and quiet, and had 5 blades.

Ended up switching out to a 75k hot dawg heater. The heater looks to have a better build wuality and works great, but the fan is way louder then the cayenne. The hot dawg heater has 3 big blades.

Does any one know if the fan's are interchangeable? the size of the fan and the shaft it mounts too looks the same, but I dont have them side by side to compare. I found the part number for the cayenne fan and would like to try swapping it on.

 

[Want2race]

First issue would be physical fitting.
You would have to look at the amp draw as well. If you put a smaller fan or different pitch you may run more amps out of the motor, which needless to say could be a fire hazard.

Have you called them and asked about it! Might just need a shroud to keep the fan from whipping the air

 

[MattFirebird]

As long as the amp draw is under the rated capacity of the circuit, no fire hazard. All common fan motors have inherent thermal protection, so even over-ampping is not a fire hazard, just a money hazard. (I've seen plenty of BURNED UP motors, but never a flaming motor. They just smoke and sizzle. You'd have to have a bunch of flamables right on the motor to cause any kind of actual fire.)
The worst problem would be if the fan doesn't move enough air, the heat exchanger cells will deteriorate early due to thermal cycling of the high limit switch.

 

[onebadbowtie86]

My buddy up the street just put in the same heater, and his sounds just like mine. Its not unbearable, I just think this heaters naturally louder then the Cayenne heater I had before this because of the fan design.

 

[thunders]

I have a hot dawg also, it is noisy

Sent from my XT1254 using Tapatalk

 

[HoosierBuddy]

I've noticed the same thing with both replacement furnaces and replacement unit heaters...that being they always seem to be louder than the old one, as far as fan/air noise.

My assumption has been that the higher efficiency units are louder than the units they replaced of lower efficiency due to decreased outlet air temperatures requiring more heated air per minute leave the unit for the same BTU/hour rating.

That's just an assumption...I've never gotten a whole lot further than wondering "Why is this unit louder than the old unit?"

To take it back to the base case, I rented a house in college (over 30 years ago) that had a gravity furnace. It sat in the basement and had no fan at all. A large standing pilot lit a large gas burner when a heat call came and besides a small amount of burner noise the unit was completely silent. Very hot air wafted up through an octopus of large round vents and comfortable heated the small 3 bedroom house through a Michigan winter for about $450 per month. I would estimate an efficiency of roughly 50% for that unit.

BTW...the rent was $280 per month.

Anyway...higher efficiency = lower output temperature = larger air volume = bigger/louder fan. My working theory until someone tells me I'm wrong. These Modine high efficiency unit heaters we have at work are VERY loud compared to the 40 year old hanging heaters they replaced.

Also to the OP...if the heat exchanger was cracked...you had to do something. Continuing to use it and hoping the CO level doesn't make someone sick or worse really isn't an option.

Phil

 

[finn]

I'd surmise that it's a matter of thinner sheet metal and less structural stiffness in the newer heaters due to manufacturing cost and profit targets.

The loss of stiffness in the unit carded all sort of NVH issues that the old, tank like structures hid by sheer mass.

 

[onebadbowtie86]

If I get around to ordering a different fan for this heater, such as the adp cayenne fan I will update this thread.