Humidifier on return or duct above furnace?

[dafreerider]

I have a heat pump system with gas backup. One pro said they always install flow-through humidifiers on duct above the furnace. The other said they prefer to install a bypass type on the return for the reason that 1) if it leaks it won't ruin the furnace (they apparently encountered that many times. 2) in summer time with cooling on they see humidifiers sweat and drip condensation when installed on duct.

What is your experience? What are pluses and minuses of each install?

[krriffle]

Makes Sense, Would Not Be An Issue Unless Above Control Side Of Furnace. But I Would Go With Steam Humidifier, If That Is Out Of Price Range Then Fan Powered Instead Of By Pass.

[ddog1]

No excuses not to go with "NEW" honeywell steamers...check them out. Price is reasonable and you can install them up to 20' remote from Supply duct.

[I_bend_metal]

A bypass will do just fine...mount it on the return duct and run the by-pass duct over to the supply above the furnace.

[cmajerus]

we install on the return and bypass to the plenum 99% of the time. For the reason of dripping on the furnace cabinet, they shouldn't but they all will at some time or another, and its cheaper to replace 4' of return duct than a furnace cabinet.

[seanc]

We always install a bypass humidifier on the return. The pad blows off at times if installed on the supply plenum.

[siltout]

Your better off going with a steam humidifier on a heat pump system. Even with the new 410 systems the supply air temperature really isn't hot enough to effectively evaporate the water enough to add moisture to the air. Also, because the air isn't as hot as the supply air from an oil or gas fired furnace, it doesn't cause as low of a humidy situation as they do either.

[I_bend_metal]

Your better off going with a steam humidifier on a heat pump system. Even with the new 410 systems the supply air temperature really isn't hot enough to effectively evaporate the water enough to add moisture to the air. Also, because the air isn't as hot as the supply air from an oil or gas fired furnace, it doesn't cause as low of a humidy situation as they do either.

Correct to a point...putting the water supply on the hot water side of the water heater will help with a bypass humidifier....when we put in heat pump systems with humidifiers the water supply is always on the hot side. Steam is a good alternative....but a bypass will do the trick as well.

[beenthere]

Also, because the air isn't as hot as the supply air from an oil or gas fired furnace, it doesn't cause as low of a humidy situation as they do either.
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Its not the discharge air temp that causes the air in the house to be dryer with gas and oil furnaces.

Older houses with oil and ND gas furnaces, seem to have higher infiltration in the occupied areas. And its the infiltration that causes the need for a humidifier.