Condensing furnace for 30 x 40?

[Innovate1]

Building a 30 x 40 garage that will be used as a workshop. Heat and AC as the summers here are hot and humid. But I want to set back when the space is not being used. Planned condensing unit because they are efficient and easy to vent. But I have read that minimum temp is an issue with damage to the primary heat exchanger. Have also read minimum temp can be an issue with 80% furnace. Radiant doesn't seem like a good idea if we are not going to be heating it all the time because of response time.

Whats a good way to do this for good equipment life and efficiency?

 

[Showkey]

True with most all heaters 80-96% ........50*-55* intake temperature is the minimum as per the manual.
That said there are many who do not flow that recommendation.( requirement).

Reality, not sure there’s all that much fuel saving from a set temp of 45* vs 55*.
Then there’s the thing...............if your out often there the raising the temp time from 40-45* to 65* working temp can take a while.

 

[Jackfre]

Rinnai EX38. Simple install, vent included as is the programmable stat which will allow as low as 38* operating temp set-point.

 

[aardquark]

Regarding the Rinnai, I just installed an EX11 this weekend in a 15x30 garage attic space (well-insulated, mostly R30 on all sides). Was very simple to install. Time will tell how well it heats.

Downstairs in the two door garage area (25x30) I use a Mr Heat 50K ceiling unit. That works fine, keeping the garage comfortable when the outside temperature is dipping down in the single digits.

 

[Jackfre]

Regarding the Rinnai, I just installed an EX11 this weekend in a 15x30 garage attic space (well-insulated, mostly R30 on all sides). Was very simple to install. Time will tell how well it heats.

Downstairs in the two door garage area (25x30) I use a Mr Heat 50K ceiling unit. That works fine, keeping the garage comfortable when the outside temperature is dipping down in the single digits.

C'mon, man!! Pictures of the Rinnai and the vent outside. Make sure you set the "set-back" feature. It will act as a low temp protection below the standard built in stat. The regular programmable stat will go down to about 55*. The set-back allows the unit to be set as low as 38* in 2* increments. Once set, even if the unit is powered off and say you had it set for 44*. the unit will turn itself on to prevent freeze-up. It is good feature to keep your paint and finishing products from freezing up in a shop.

 

[Showkey]

Regarding the Rinnai, I just installed an EX11 this weekend in a 15x30 garage attic space (well-insulated, mostly R30 on all sides). Was very simple to install. Time will tell how well it heats.

Downstairs in the two door garage area (25x30) I use a Mr Heat 50K ceiling unit. That works fine, keeping the garage comfortable when the outside temperature is dipping down in the single digits.

No question the EX11 will heat that space.
1200 sqft total well insulated a single 50k unit should heat that total space with no trouble.

I do 1000 sqft stand alone shop well insulated in a very cold climate ( 0 to -30*) with 40k. It had a 60k unit that failed from old age.

 

[ripperd]

Missouri, heat and AC? Sounds like a good application for a minisplit that has a heat pump mode. Probably not a whole lot more expensive than gas in heat mode, and less equipment cost.

 

[Innovate1]

Missouri, heat and AC? Sounds like a good application for a minisplit that has a heat pump mode. Probably not a whole lot more expensive than gas in heat mode, and less equipment cost.

I would be interested to see some information on efficiency/cost in my climate. These were suggested by some HVAC contractors but I don't know much about them. It would eliminate the issue with low inside temp.