Heating a large garage .... need real world advice please
- Thread starter xtal_01
- Start date
IMO, the online calculators are way over sized. It has been discussed here before.
The calculator he used is actually ok, I've used it before.
I punched some numbers in based on the location, 4000 sqft and the construction mentioned in the original post. It spit out about 70,000 BTU for the whole shed.
That means you'd be looking for around 90,000 input assuming an 80% heater
I punched some numbers in based on the location, 4000 sqft and the construction mentioned in the original post. It spit out about 70,000 BTU for the whole shed.
That means you'd be looking for around 90,000 input assuming an 80% heater
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(4) Diesel salamander heaters and crack a window open?
you're somewhat mistaken on this.
condensing furnaces need freeze protection (condensate can freeze and plug traps/HX), but for either a 80% or condensing you can put a bypass duct, damper and a simple thermostat on it to bleed heat into the return plenum until the space is warm enough for proper operation (non-condensing operation in the primary HX). this could be as simple as a 55F snap disc in the return and a 24V zone damper. it would not affect delivered BTU.
theoldwizard1
Well-known member
Mini-split heat pump with multiple air handlers is an option. The problem is large compressor unit with multiple air handlers are not super efficient. Something your size would require 2 maybe even 3 compressors. Now we are talking some real $,$$$ ! Even though they are typically more cost effective than natural gas and cheaper to install (especially if the gas needs duct work), this type of installation would have a LONG pay back time !
The good news is, they are easy to program for different comfort levels in different rooms. (Not really a bonus for you but there is no extra installation charge for A/C and humidity control.)
Last bad news is, it you have plumbing in the building or other thing that would freeze or be damaged without heat during an extended power outage, you need a big backup generator or alternative source of heat.
The good news is, they are easy to program for different comfort levels in different rooms. (Not really a bonus for you but there is no extra installation charge for A/C and humidity control.)
Last bad news is, it you have plumbing in the building or other thing that would freeze or be damaged without heat during an extended power outage, you need a big backup generator or alternative source of heat.
those are the cases where a small generator/lithium pack + heat tape are often warranted.
some of the LFP "portable generators" even have UPS-like modes where they'll pass power and switch to the battery if the power goes out. way cheaper per hour of runtime than a traditional lead acid UPS.
We've a PTO generator for such rare events. 4 days was the most recent long one. fortunately, inverter heat pumps are much easier on inrush than PSC compressors.
HoosierBuddy
Well-known member
I'm thinking natural gas hanging heater all day for your situation based on:
1. NG is available
2. You only want to heat minimally with the ability to bring the temperature up to a more comfortable level perhaps when you are working out there.
That just screams NG hanging heater to me and you'll actually want it to be oversized somewhat so you can bring the temperature up rapidly from (say) 45 degrees to 65 degrees if you want to go work out there on a Saturday morning.
The whole 3 bays thing though makes using a single hanging heater problematic. For separate areas like that, a ducted solution would be more appropriate. So now you're back to talking about a NG furnace with ductwork. Zone Control could be added with automatic dampers, but I don't think I'd mess with it too much.
With a high efficiency NG you will have to leave it on all winter to protect against freezing the condensate lines.
Hmm...I'd almost look at going with 2 small Modine Effinity93 heaters and put them on the outside bays only. Leave a tee in the NG line where it crosses between the bays so you can add a third if you need to for more comfort down the road. The Effinity93 line starts at 55,000 BTU/hour. A unit that size is roughly $1700 each.
1. NG is available
2. You only want to heat minimally with the ability to bring the temperature up to a more comfortable level perhaps when you are working out there.
That just screams NG hanging heater to me and you'll actually want it to be oversized somewhat so you can bring the temperature up rapidly from (say) 45 degrees to 65 degrees if you want to go work out there on a Saturday morning.
The whole 3 bays thing though makes using a single hanging heater problematic. For separate areas like that, a ducted solution would be more appropriate. So now you're back to talking about a NG furnace with ductwork. Zone Control could be added with automatic dampers, but I don't think I'd mess with it too much.
With a high efficiency NG you will have to leave it on all winter to protect against freezing the condensate lines.
Hmm...I'd almost look at going with 2 small Modine Effinity93 heaters and put them on the outside bays only. Leave a tee in the NG line where it crosses between the bays so you can add a third if you need to for more comfort down the road. The Effinity93 line starts at 55,000 BTU/hour. A unit that size is roughly $1700 each.
There can be reasons to oversize somewhat, large temperature setbacks like the op is planning.
But three 75,000 heaters (225,000 total) when the building needs less than 100,000 total is not a great plan.
A grossly oversized heater is actually less effective for large setbacks because it warms up the air quickly but cycles off before any of the things in the shop can warm up. Once the heater cycles off it quickly feels cold again. You can get around this problem with two-stage heaters or multiple heaters in the same bay. I would just keep it to no more than 150% of a good load calculation.
But three 75,000 heaters (225,000 total) when the building needs less than 100,000 total is not a great plan.
A grossly oversized heater is actually less effective for large setbacks because it warms up the air quickly but cycles off before any of the things in the shop can warm up. Once the heater cycles off it quickly feels cold again. You can get around this problem with two-stage heaters or multiple heaters in the same bay. I would just keep it to no more than 150% of a good load calculation.