Hello all,
I am building a pole barn garage with a 575 sf (16×36) loft apartment above it in northern MI. Cold. It will be used all year as the cottage for a few years then later as a guest house when we build a cottage. It will have 1 small bedroom, a 3/4 bath and the rest open.
I think it will have minimal use in winter when it is a guest house because I don’t expect overflowing winter guests when it is 5-below!
I am not sure how to heat it. Electric or propane, no natural gas. Energy cost is a consideration.
I believe I will need to have a conditioned room under the loft for water pipes to go through to underground so they do not freeze, so that space (roughly 8×16, directly under the only plumbing in the loft) also needs to be kept above freezing.
I was thinking air source mini-split to also get some cooling upstairs but the local builder said it will underperform in the cold and risk going below 40 degrees when we are not using it. Also said it will take forever to heat up so when we come for a winter weekend it take hours to get to 65 degrees. Additionally, Mini split does not heat the mechanical space below.
What solutions do you think are best and most cost effective for heating and hot water?
I like the idea of solar but the area is wooded and the nearest clearing for a small ground array is about 250-300 ft away.
Thank you!
Jim
Replies
I have a similar set up in CT, Zone 5. My Mitsubishi mini-split pumps warm air at -15F outdoor temp. There's never been a problem keeping the place warm. If you do a good job insulating and air sealing, even if it does get below the mini-split's capability occasionally, it should still be fine.
The magazine has several articles on minisplits. This one was photographed at my place. https://www.finehomebuilding.com/2016/03/02/how-to-install-a-minisplit
Thank you, Andy. Love mini splits if they fit my application. Do you ever drop the heat down to 45 when gone for weeks at a time and have to increase indoor temp quickly? Wondering how quickly it can heat the space. Thank you.
I never drop it that low. I'm not sure it goes that low! We keep it around 60F when it's unoccupied. If you want to heat the place up quickly, use a portable electric heater. We used to keep one up there for our guests, but no one ever used it so I use to warm my shop when I don't want to bother with the wood stove.
I lived in Ann Arbor for 3 years, so know how cold MI can get. Mini’s can work great, but many factors to consider. Only an Hvac engineer can offer the best advice. I would urge you to seek one out. I’m lucky as I have an HVAC supply company here that provides in house engineering for free. How tightly sealed, insulated and etc your loft is plays a huge part in determining the best approach. Where I live now is just as cold as MI and most applications here call for hyper heat function to the mini. It brings the cost up a bit per unit and when running in hyper heat mode it isn’t the most economical to run. I recently built an apartment at 580 sq ft. When you take into account the need for hot water along with heat my engineer and I decided to go with a combi boiler set up with radiant heat. Can use radiant floors or wall hung radiators. Combi boilers are instant hot, so do not take up a lot of space like a tank heater. For A/C we found a simple energy efficient through wall A/C unit. At 580 sq ft we only needed one A/C unit to adequately cool the space.
Also, it’s advised in my parts to never set thermostat lower than 50 in winter. If you go lower than that you risk pipes freezing. I don’t go any lower than 60 like Andy. I’ve found wood trim and cabinets are less likely to shrink and expand with temp and humidity changes by maintaining a somewhat constant temp between seasons.
Excellent comments, thank you. I currently have a combo-core nat gas HWH in my house for in-floor radiant and domestic hot water. Works great and cost to operate is acceptable because we are on natural gas.
What powers your boiler?
It is powered by Natural Gas, but requires an electrical hookup for igniter etc. I think there are a few electric options in the market, but most are gas. Efficiency probably drops substantially with electric vs gas, but I haven’t checked on that for awhile. There might be a really efficient electric available now.