unit heaters

bob young

Always thought modine was top of the line. new models can probably measure up to any other vendor. i got a issue with a modine going on presently & hope the factory support is friendly.

ttekushan_2

quiet steam unit heaters?

Greetings.

I would like to spec a couple of steam unit heaters for a grocery store type space. The building is an old industrial building so that is to remain the basic design theme. So steam unit heaters are a good fit. The steam system is being expanded into this area, since the system was set up to heat this space but never has. The live steam main and return system go up to this newer (less old?) space and are properly sized for the necessary load. The boiler also happens to be sized for the existing building plus the new load!

Wall space is at a premium due the coolers and shelving.

Unit heaters will do the job well except for the fact that the others around the facility are all very noisy. They are Modines. There is one unit that is a very old Dayton that is acceptable in noise, but I can't seem to find any information on their new product, or their web site for that matter.

Are there any quiet unit heaters out there???

-Terry

Brad White_17

Unit Heater Thoughts

Just some thoughts for your consideration, some you may already be entertaining:

If possible I favor vertical discharge unit heaters. They act as destratification fans as a bonus. They also come in low-temperature versions whereby they have ports which open to dilute the air temperature. (Too hot and the air buoyancy issue arises if the units are up too high. Air will not reach the floor as well.)

It is entirely subjective but I find them less noisy than horizontal units in very general terms. It may be that the horizontal units have more items in the airstream and blow through the coil and outlet louvers.

The vertical ones have outlet cones and louvers too (I like the adjustable kind!) but adjustment is the variable here as far as noise is concerned. Vertical units draw the air in rather than force the air against a coil, so as a principle of operation I see them as quieter.

Either can be selected noisier or not, so what I am describing is a tendency, not an absolute.

When selecting for noise, I would select for the lowest practical RPM to do the job, but the real key to fan noise is tip speed. RPM alone is half the story. A 30 inch fan at 1100 RPM has tip speed of about 8600 FPM and a 24 inch fan at 1100 RPM has a tip speed of about 6900 FPM. Noise is subjective and without specific criteria, I like to stay below 6000 FPM. Of course mounting height and unit selection govern within that.

For further noise reduction, I specify varible speed controllers (fractional HP, they cost about $20) to manually adjust for a balance between comfort and noise. A hobson's choice sometimes but it is cheap insurance. The VS controller works better with the low temperature units because you can reduce the temperature to promote "drop" at lower fan RPM/CFM. Trial an error adjustment.

And yes, Modine has good quality, selection and distribution. There are others of course.

Hope this helps.

Brad