: Radiant heater vs forced air heater for a garage workshop - pros and cons?


MACenstein'sMonster
Aug 12th, 2009, 06:37 PM
I've done some reading, now, once again, I look to you guys for other opinions.

I have a 24'X24'X10' garage that will be gradually turned into a workshop. The type of work that will done in the shop will consist mainly of woodworking.

So far I'm leaning heavily towards having a direct vent radiant heater installed. A direct vent forced air unit would cost about the same but I would have to worry about it blowing dust onto my projects if I'm doing some finishing. That's one reason I'm considering the radiant heater - doesn't move air in the shop around when heating.

Some people have suggested that if you're standing beneath a radiant heater it can get toasty on the head. Plus there are clearances both above and below that need to be in place and thus the radiant heater uses up more space than a forced air unit. I don't think I'm too concerned about that.

The latest I've heard concerning radiant heat is that it can remove too much moisture and leave the air in the room a little too dry. This is news to me and I've never heard it suggested before. In fact, I've heard and experienced that any direct vent heating appliance usually leaves more humidity in the room because less can escape unlike heating appliances that vent out a conventional chimney. Anybody have thoughts or info on this? Thanks in advance.

eMacMan
Aug 12th, 2009, 09:11 PM
Several Scotsmen in this part of the world swear by the radiant heaters simply because of the energy savings.

ChilBear
Aug 12th, 2009, 10:00 PM
I think your room is too large for radiant to work efficiently and suggest a very low speed forced air with a serious filter on the intake side. Is you catch the dust on the intake then it cannot be moved around. Make sure the intake is as far away from the prime area as possible.

dona83
Aug 12th, 2009, 10:10 PM
Too large? It's perfect for two of radiant heater panels. I'm just concerned about the low head room, I don't like to see radiant heaters installed below 12' A.F.F.

Chilbear has a good suggestion. Filter -> Fan -> Heater (6 or 8 inch) -> Grille, all connected with 6" or 8" duct. Make sure there's 24" of free duct between the heater and anything.

ChilBear
Aug 12th, 2009, 10:31 PM
On thinking further, have you considered that the room may be stratified temperature wise (cool at the floor) and how that may impact drying? Warmer on top and cooler on the bottom is not good for wood and certainly not for finishes. You need to get the room stable and not have warm / cold zones.

MACenstein'sMonster
Aug 13th, 2009, 04:04 AM
The radiant and forced air heaters I've been looking at are direct vent. Wouldn't the majority of the air that a direct vent forced air unit use be taken in from outside the room (garage)?

In any case, I'll have dust collection set-up. A dust collector that collects right off the tools themselves and an ambient dust collector that captures smaller particles in the air.

As for radiant heaters, I'll have a professional install the unit if I go that route. But radiant heaters come in all sizes and a 45,000 BTU unit is recommended for a room of my size. Radiant heaters work best, apparently, when there is a lot of floor/concrete exposed. The heater is mounted so that it points at an angle down towards the floor. The radiant energy heats objects, not the air. So the floor is heated and the resulting heat rises up (I assume this is why it's best to have a large area of open floor).

As for the radiant heat causing problems with finishes, paint, etc? Well, it's thermostat controlled so I'm thinking I'd be able to keep it in check or just make sure finishing takes place far away from the heat source.

I was told that radiant heaters dominated the market for heat installations in detached garages at one time. Now that forced air units have shrunk down in size it's quite the opposite. When I tell installers that it's going to be a workshop, mainly woodworking, many of them seem to agree (not all) that radiant heat might be the best for my situation.

MACenstein'sMonster
Aug 13th, 2009, 02:15 PM
I posted a reply (#6) but it only shows 4 replies in this thread. Weird.

screature
Aug 13th, 2009, 03:36 PM
I have a neighbour with a woodworking shop about the size you are talking about (and it is fully detached from the house so there is no benefit of heat from the house) she uses two radiant heaters and I have been in it in the dead of winter and it was plenty toasty.

Also as far as being dry goes, even if it is true, dry is good for wood so what is the problem with that anyway.

MACenstein'sMonster
Aug 13th, 2009, 04:37 PM
I have a neighbour with a woodworking shop about the size you are talking about (and it is fully detached from the house so there is no benefit of heat from the house) she uses two radiant heaters and I have been in it in the dead of winter and it was plenty toasty.

Also as far as being dry goes, even if it is true, dry is good for wood so what is the problem with that anyway.

Depends. Wood moves (varies with species) with changes in climate (humidity). For example, I've seen a situation where a wood carving was brought to woodworker's guild meeting and the question was asked "why is it cracking after years of being just fine?" The first response was a question, "where did the carving reside all the years it was fine?" Answer - "up until recently, at the lake". He was told to take it back to the lake :) Had the conditions of this man's home in the city resembled the climate conditions of the lake then likely the carving would've been fine. Obviously, the man's home in the city had "drier" conditions (less humidity) and thus the cracks developed as the wood carving dried and shrunk (moved).

Another example. My wife and I bought a piece of antique furniture originating in Europe at a local store several years ago. I remember seeing a lot of humidifiers in the store. At the time, it never dawned on me what the REAL purpose was since I wasn't aware of the problems with wood furniture and climate change. Needless to say, within a couple years the piece started to develop cracks in the marble top and some of the joints loosened. This was likely due to wood shrinkage from our house being too dry relative to the conditions the furniture piece was originally subject to. Very common problem even with modern wood furniture built overseas.

Therefore, with that in mind, climate control is important when building with wood. Certain species of wood will move a lot. If the workshop becomes excessively dry it could raise hell with material with regards to warping, etc. or make glue joints a real nightmare. Shops heated with wood stoves would combat this problem by putting a pot of water on the stove. But I've never heard anyone mention this problem with regards to radiant heat until now which is why I'm curious as to where this information comes from.

screature
Aug 13th, 2009, 05:46 PM
Yes I know where you are coming from as we have a large amount of furniture that was made in Mexico and now that is in our much drier climate it does make for some "interesting" problems.

I guess the point that I was trying to make is that as long as the humidity remains relatively constant in your shop that is the best that you can hope for and in general, drier is better (i.e. kiln dried wood is better to work with than green wood).

You cannot control the environment that the wood was in prior to coming into your possession and unless you have different environments to store the wood in that reflect the environments that it was kept/built in prior to your acquiring it, there will always be issues, but in general for wood, dry is good.

Lichen Software
Aug 13th, 2009, 11:29 PM
1. A primary thing that you want in a wood working shop especialy if you are finishing is no open flame including pilot light. So you are looking not only for a direct vent for the exaust but also for a separate air intake for combustion in comination with a sealed (from the inside) combustion chamber. Then when you varnish, you won't go boom.

2. If you can control the dust thing, I would think a forced air versus radiant might be better. The air would be the ambient temparature of the objects you are working on. A temperature differential could cause strange things when finishing.

3. You will have increased humitity if you have a sealed combustion chamber with an outside air draw. In old style furnaces, burning inside air, there is always a negative interior pressure because air is being constantly pumped up the chimney. This air is replaced by exterior air dragged in through small openings inthe building envelop which is cooler and hence as it warms up has a very low relative humidity.

Think of it this way. The warmer the air is, the more water it can hold. So if you drag air in that had a relative humidity of say 80% at 0 degrees C into a garage/shop kept at 20 degrees C. once that air warms to 20, that air can hold all that it could outside plus a whole lot more. The relative humitity could drop from 80% down to say 50%.

wslctrc
Aug 13th, 2009, 11:43 PM
I agree with what screature is telling you. The shops I've wired or done service calls on use an assortment of heating units and the forced air units are mainly in shops or garages that don't concern themselves with airborne particulate. All the wood shops I service have radiant heaters with humidifiers to control the humidity level. This is the way I would go, no dust kicked up when the furnace kicks in and a humidifier that kicks in when needed.

MACenstein'sMonster
Aug 14th, 2009, 05:06 AM
Yes I know where you are coming from as we have a large amount of furniture that was made in Mexico and now that is in our much drier climate it does make for some "interesting" problems.

I guess the point that I was trying to make is that as long as the humidity remains relatively constant in your shop that is the best that you can hope for and in general, drier is better (i.e. kiln dried wood is better to work with than green wood).

You cannot control the environment that the wood was in prior to coming into your possession and unless you have different environments to store the wood in that reflect the environments that it was kept/built in prior to your acquiring it, there will always be issues, but in general for wood, dry is good.

The examples I gave were finished items that had been moved from one environment to another, where the second environment is significantly different. This was simply to illustrate how climate change can dramatically affect wood.

Rough stock that's meant to be used for furniture building etc. can be conditioned to a new environment if it's allowed to "season". Depending on the condition of the stock (kiln dried, freshly milled, etc) this can take days, weeks, months or even years. Once it's seasoned then it's ready to be processed. Should the large dimension material warp, twist, cup or bow :D the smaller dimensional finished stock can likely still be machined from it. But damaged furniture due to similar movement is a much more difficult task.

Point is, nobody machines stock until it stabilizes and is "seasoned". If it arrives green it sits until it reaches a proper moisture content. Old timers knew this without a moisture meter. Even if it's "kiln dried" most experienced woodworkers would check the moisture content and let it sit in their shop for a period of time before using it.

Back to my concern. I'm still researching where the idea of radiant heat creating a dry environment comes from. Obviously, I can create humidity in my shop like I can in my house if the level of humidity gets too low. But is a lower humidity in my shop expected because it's radiant rather than forced air?

MACenstein'sMonster
Aug 14th, 2009, 05:57 AM
Just to make sure we're all on the same page this is the type of GAS powered radiant heater I'm referring to:

GORDONRAY BH Infrared heater (http://www.rg-inc.com/GRBH-Infrared-Heater.htm)

Should have been clearer in my description I think :o

Everyone I talk to refers to these units as radiant heaters as opposed to infrared heaters. Seen all kinds of variations. Never can be too precise.

screature
Aug 14th, 2009, 11:26 AM
The examples I gave were finished items that had been moved from one environment to another, where the second environment is significantly different. This was simply to illustrate how climate change can dramatically affect wood.

Rough stock that's meant to be used for furniture building etc. can be conditioned to a new environment if it's allowed to "season". Depending on the condition of the stock (kiln dried, freshly milled, etc) this can take days, weeks, months or even years. Once it's seasoned then it's ready to be processed. Should the large dimension material warp, twist, cup or bow :D the smaller dimensional finished stock can likely still be machined from it. But damaged furniture due to similar movement is a much more difficult task.

Point is, nobody machines stock until it stabilizes and is "seasoned". If it arrives green it sits until it reaches a proper moisture content. Old timers knew this without a moisture meter. Even if it's "kiln dried" most experienced woodworkers would check the moisture content and let it sit in their shop for a period of time before using it.

Back to my concern. I'm still researching where the idea of radiant heat creating a dry environment comes from. Obviously, I can create humidity in my shop like I can in my house if the level of humidity gets too low. But is a lower humidity in my shop expected because it's radiant rather than forced air?


I think we are actually agreeing just coming from different directions. At any rate as I said my neighbour who is a professional woodworker uses the radiant heaters without any apparent issues so I don't think it is of any real concern. I certainly see no logical reason for why radiant heat would be more drying than forced air.