Warehouse heat

[Green Mountain]

A customer asked me to design a new system for his warehouse.

The area was designed as a production area when it was built 20 years ago.
And as such it has CO-Ray-Vac infarad heaters.

Now the warehouse is used to store wood pallets. These are stacked close to the infarad heaters. The infarad heaters are old, some are burnt out and cannot be serviced because of the pallets being in the way.

So I am wrestling with what to install. Energy is an issue. These run on propane, therefore, we would like to get something in the 90% range.

I would appreciate it if we can kick this project around and let me pick your brains.

[beenthere]

The IRs are still going to be cheaper to heat with then a 90% furnace.

Do you have enough room on the perimeter to use IRs.

How warm do they need it, just to store pallets?

[hvacker]

I thought you retired Benn.
Anyway IR's like Beenthere said will be way cheaper to run. The Co-Ray-Vac's I work with have the controls on one end. Maybe the pallets could be arranged to accommodate this.
Being a warehouse it probably isn't very tight.

[bob_scheel]

A customer asked me to design a new system for his warehouse.

The area was designed as a production area when it was built 20 years ago.
And as such it has CO-Ray-Vac infarad heaters.

Now the warehouse is used to store wood pallets. These are stacked close to the infarad heaters. The infarad heaters are old, some are burnt out and cannot be serviced because of the pallets being in the way.

So I am wrestling with what to install. Energy is an issue. These run on propane, therefore, we would like to get something in the 90% range.

I would appreciate it if we can kick this project around and let me pick your brains.

What is the cost for the LP gas in this area? What is the cost for electricity?
Unless your electric rate is very high the LP is going to be more expensive than electric resistance heating. Electric radiant heaters might be your best bet due to low equipment costs. Heat pumps or geothermal if you can get a decent payback time.

[ascj]

Rip up the concrete, drop some radiant loops in, and install a 90% boiler. All kidding aside, the most efficient way to heat a warehouse is some form of radiant heat.

Does the warehouse have dock bays? What temp are they trying to maintain? Is it just storage?

[Green Mountain]

Right now the owner just wants to keep his building from freezing up. (sprinklers etc.). But that may change if he gets an new tenant.

Electric rates are outrageous here in VT. The ski industry uses a lot of electricity in the winter. So to be fair the rates double in the winter and go down the rest of the year. This way the average user is not shouldering the cost of the ski industry. All of our power comes from Canada.

So I would say that propane is the fuel we must use.

One time I looked at some specs for a UPS warehouse. The spec had one big unit in the middle of the space that sat on the floor and blew the heat out 4 sides. We didn't get the job so I forgot who made it. Does anyone know of this type of unit.

The problem with IR heaters is that they heat what they see. The ones we have now are "seeing" the pallets and not the concrete floor.

[thump_rrr]

When I worked for Engineered Air we made some indirect fired units such as these.
Blowers at the bottom drawing from all sides blowing upwards through the HE and out directional goosenecks.
I have a customer with some 40 year old Dravo conversion furnaces made the same way.

[ascj]

We take care of 7 UPS buildings. They use Rapid MUA units. They have a national account with them. They use them, because they also have alot of ventilation. Picture a building with 300 trucks starting up and the same time, you get the picture. They are extremely expense to run compared to radiant heaters. Their gas bills range from 15k-120k a month, depending on the locations building size. For small packing location we use radiant tube heaters.

[bob_scheel]

Right now the owner just wants to keep his building from freezing up. (sprinklers etc.). But that may change if he gets an new tenant.

Electric rates are outrageous here in VT. The ski industry uses a lot of electricity in the winter. So to be fair the rates double in the winter and go down the rest of the year. This way the average user is not shouldering the cost of the ski industry. All of our power comes from Canada.

So I would say that propane is the fuel we must use.

One time I looked at some specs for a UPS warehouse. The spec had one big unit in the middle of the space that sat on the floor and blew the heat out 4 sides. We didn't get the job so I forgot who made it. Does anyone know of this type of unit.

The problem with IR heaters is that they heat what they see. The ones we have now are "seeing" the pallets and not the concrete floor.

I'ld go with hanging heaters like Reznor or similar. You should be able to hook them up easily to the existing LP gas lines and flue pipe. If the majority of the vulnerable piping is in the ceiling space you should be able to keep the costs down by mounting the stats on the side of the unit so they see the temp near the sprinkler piping. Areas that have piping lower down can have units mounted w the air directed downward and the stat on the wall. Make sure the customer deals w any air infiltration issues as well.

[Lash]

I agree on the unit heaters.....as long as they are higher efficiency ones.

[ascj]

Indirect fired unit heaters are by far the 2nd worst way to heat a warehouse. You are dumping heat out the chimney and trying to heat the air by pure convection. The first being, electric resistence heaters.

Here's good article on warehouse heating- http://www.cambridge-eng.com/case_studies/warehouse_heating.asp

Don't pay attention to there bias option, it's just a good article to show the different options and pros and cons.

[Green Mountain]

Indirect fired unit heaters are by far the 2nd worst way to heat a warehouse. You are dumping heat out the chimney and trying to heat the air by pure convection. The first being, electric resistence heaters.

Here's good article on warehouse heating- http://www.cambridge-eng.com/case_studies/warehouse_heating.asp

Don't pay attention to there bias option, it's just a good article to show the different options and pros and cons.


Wow! There is some dynamite information in that article. Thanks a lot, that's was what I was looking for.

[bob_scheel]

Indirect fired unit heaters are by far the 2nd worst way to heat a warehouse. You are dumping heat out the chimney and trying to heat the air by pure convection. The first being, electric resistence heaters.

Here's good article on warehouse heating- http://www.cambridge-eng.com/case_studies/warehouse_heating.asp

Don't pay attention to there bias option, it's just a good article to show the different options and pros and cons.

They are assuming that substantial amounts of outside air are necessary for ventilation. This is true in an occupied warehouse w fumes from lift trucks or manufacturing processes. It is NOT true for an empty or storage only warehouse. Indirect fired are more efficient in the case where fresh air is not needed.

[ascj]

They are assuming that substantial amounts of outside air are necessary for ventilation. This is true in an occupied warehouse w fumes from lift trucks or manufacturing processes. It is NOT true for an empty or storage only warehouse. Indirect fired are more efficient in the case where fresh air is not needed.

I said don't pay attention to Cambridges bias opinion on there units over others. The posts above were talking unit heaters, I'm going to assume they were referring to infirect fired hanging unit heaters. Assuming radiant is out, a direct fired unit wills always be more efficient than an indirect fired unit. Im not a big Cambridge fan, it was just an article to look at. Let take a direct fired recirculating return heater and but it up to a indirect fired unit heater. You are only pulling enough outside air in for proper combustion and every cf of gas is going to heating the space, plus the space will be in a slight postive. The indirect is going to dump 10-20% of your cf of gas out the flue and put the building in a negative.