How often should a Big Maxx kick on/off?

[bobs409]

I started using my new Big maxx 80 btu but I've only run it manually for now. I noticed it wants to kick on for just a short time after heating the garage to the set temp. I'm worried about this as it seems like this will wear out the heater parts such as the ignitor, etc.

Now I haven't had it on for a full day so maybe I'm jumping the gun but here's a scenerio:

Garage about 48 degrees in the morning. Turn heater on and set to 60, it runs as it should and heats up in a decent amount of timetehn shuts off. About 10-15 minutes later, it kicks back on again and only runs for a few minutes, then shuts off. Probably another 15 minutes or so and back on. While I didn't actually clock it, I think it spanned a little longer after that but isn't this excessive? Perhaps if it was left on continuously, it might run a little less frequent when everything inside the garage got up to temp. ?? The only problem is I would want to lower the temp for the night time hours down to about 50 when I'm not in there so the next day, I'd be back where I started. (hope I didn't lose anyone, not real easy to describe) lol

How many times does your heater kick on/off? I only have a round type thermostat, maybe a digital type would work better? Can they be set more acccurately say, kick on at 55 and shut off a 65? Something like that would make more sense than on/off every 15 minutes. I need something not so sensitive I guess??

Not sure if it matters in answering my general question but my garage is a 2.5 with 2X4 walls and insulated. Has insulated garage doors, I think 1-1/2 thick if memory serves. I know it's not as well insulated as we would all like but should be good enough I would think.


Your thoughts...

 

[A_Pmech]

The duty cycle of the heater depends entirely on the heat load of the room and the differential temperature setting of the thermostat.

No, it won't "wear out" your heater. It's performing as it's designed to. Think about it. The igniter on my heater cycles for about three seconds at 60 Hz, that's about 180 sparks per ignition interval. Even a ****** automotive spark plug is good for 20,000 miles, which is about 15,000,000 sparks, or 83,333 heater ignition intervals.

With a 50% duty cycle at 15 minutes on, that's 83,333 (30 minutes) = ~42,000 hours of operation.

 

[Basstracker34]

How many square feet is your garage?

 

[bobs409]

It's about 750.

 

[CNGsaves]

Reason for quick cycling of Big Maxx 80K Btu heater is OVER sizing for your 750 sq ft garage.

Won't hurt the heater in whole scheme of things, just shorter run times.

You likely would have been fine with 50K or 60K Btu heater, assuming you have insulated walls & ceiling in 750 sq ft garage. Also, depends if your garage is battling "cold" in Canada or Miami, FL.

Now would be good time to Update GJ Profile with City / State / Country.

 

[bobs409]

I'm in PA. If I remember correctly, the 50k unit was supposed to be good up to about 700 sq ft so I chose the bigger one since my garage was over that.

Will update my profile...


Thanks,

 

[mygarageone]

I'm in PA. If I remember correctly, the 50k unit was supposed to be good up to about 700 sq ft so I chose the bigger one since my garage was over that.

Will update my profile...


Thanks,

The old saying bigger is not better , especially when it's heating equip.
And it will prematurely wear parts out , short cycling is the worst thing for any equip.
By the way equipment should never be sized by square footage. People who size equipment this way haven't a clue.
You maybe able to reduce the btu rating with orfice changes , that's determine by the manufacture.

 

[RustnGrease]

Bob,Can't really help on the heater issue but noticed you're right up the road (5 miles) from me.

 

[AlbertaSS]

bob- I wonder if you put the thermostat in the coolest part of the garage and increase the adjustment between cycles on the thermostat if that would help.

 

[bobs409]

I believe I have the stat in the coolest part now. I have the heater on a 45 degree angle pointing toward the biggest air loss (garage doors) and the stat is under the heater so it gets only the returning air. I can actually feel the air flow and the difference in temps myself as I move around in the garage. I also have a ceiling fan I set on low to pull air up from the center of the garage and push it back down toward the walls. I have this because 1/2 of the garage has a 4 post lift and a high ceiling. (other half is an enclosed insulated loft)

How does one adjust the cycle time on this? Sounds like just what I need. Would like to make it not so sensitive. If I set it to 60, I don't need it to work so hard to maintain that exact setting. I'd be happy if it kicked on at 55 and shut off at 60 so maybe a 5+ degree range. (If something like that is even possible)

 

[bobs409]

Bob,Can't really help on the heater issue but noticed you're right up the road (5 miles) from me.

I probably see you all the time then.

 

[bobs409]

Now you got me thinking about the cycling time or "dead band" setting. This is probably just what I need! I searched online but I'm still confused on this.

Do I need a thermostat that has Heat & AC settings to be able to adjust this dead band?

If so, does that mean if I want say a 5 degree dead band so it kick's on at 55 and shuts off at 60, I would set the heat at 55 and the AC at 60??? (even though there is no actual AC unit)

It's early and my brain isn't up to operating temp yet so help me understand this.

 

[mygarageone]

You can adjust some of your issues by the heat anticipator on the thermostat.

 

[JCByrd24]

My Hunter 44110 programmable has a setting called "span" that is exactly what you are talking about, many thermostats do. If you are ok with the swings in the garage set your span to the largest and it will reduce the cycling. I agree that cycling is not great. You want the heater and exhaust to come up to full temp to burn off any condensate etc. It's also using excess gas ever time it come up from cold iron, though these units warm up fairly quickly. As a reference I'm in Maine and my garage is 768 sq ft and I ended up with a super deal on a 30K BTU/hr unit but once insulated it will be enough.

I do believe you can probably reduce the orifice size as long us the 80K isn't the lowest output of that frame size.

 

[RustnGrease]

I probably see you all the time then.

Probably. You're the guy that gets to all the sales before me and gets the good deals. At least in my head....

 

[James-W]

My garage is 864 square feet and I have a 60,000 BTU Hot Dawg heater. I leave the heat on all Winter long, but I turn it down to 50 degrees when I am not working out there. While working on a project I turn it up to 70 degrees. The walls have R-19 insulation and the ceiling has R-30 insulation. Depending on how cold it is outside, the heater will turn somewhere between 15 minutes and 30 minutes and will run for maybe 3 - 5 minutes before turning off again.

 

[bobs409]

Today I went for the gusto and bought the wi-fi stat by Honeywell and installed it. I noticed an improvement right out of the box. It has a 3 degree dead time and I can of course increase that if needed. Heater ran until it hit the called for temp and shut off. It did not keep coming back on/off like the old one. Maybe that one was too sensitive or set less than 3 degrees. ??

Now I can control my heat right from my computer too!

 

[dave67fd]

Can we assume you have the thermostat on an outside wall? I realize many/most garages don't have an interior wall for mounting so if not, spacing it off on a piece of insulating foam helps.

 

[bobs409]

I have another attached garage that is unheated. Stat is on that wall under the heater so should be ok there.

 

[curiousB]

If the round thermostat is the old mercury switch type you perhaps need the anticipator. It is a small lever inside. The numbers refer to the current in the thermostat loop. You should measure the current with an AC ammeter and use that value to set the lever.



Check out this video on YouTube:

Sent from my iPad using Tapatalk

 

[JAckal]

My digital/programmable thermostat has an adjustable "span".
If you set it on 65*, it heats up to 67* then shuts off. When the temp gets down to 63*, it comes back on.

I could change then span, but it works great like it is.

If you put it on "hold", it tries to hold the temp exactly what is is set for.

Jack

 

[bobs409]

Can you share what brand/model of stat you have? I can't seem to find any with a way to set the deadband.

 

[JAckal]

Bob,

The one in my house is a Hunter brand. They call it adjustable span, swing, or hysteresis. The one in my old house was a Robert Shaw. < The Robert Shaw was a $200 thermostat that I got from a contractor. He had it leftover from a house build, and the owner didnt like it.

Both of these thermostats were installed on heat pump systems. I am not sure if they are available for other systems. When looking at them in the store there is a big difference in how they operate, so the package has warnings that heat pump, and regular CH &A won't interchange.

I'll try to find the model number on mine.

Jack

 

[jdcompman]

Reason for quick cycling of Big Maxx 80K Btu heater is OVER sizing for your 750 sq ft garage.

Won't hurt the heater in whole scheme of things, just shorter run times.

You likely would have been fine with 50K or 60K Btu heater, assuming you have insulated walls & ceiling in 750 sq ft garage. Also, depends if your garage is battling "cold" in Canada or Miami, FL.

Now would be good time to Update GJ Profile with City / State / Country.

This! Is the root of your problem. The new thermostat will help your problem but the main problem is the heater is oversized. Had a 45k in my old 750 sq ft garage and it kept up just fine. I can't imagine twice that size in that space.