Furnace in Workshop?

[Charles Murray Ohio]

I built my shop last year. After getting a quote, I installed it myself. A friend on my who is an air systems engineer designed the system (duct sizes and location, BTU and AC size). One of the things he recommended was to upsize the blower due to the 10’ ceilings. The system works great, better than the professionally installed one in my house. I used a 95 plus natural gas furnace, that has sealed combustion. A concentric vent brings in fresh air for the unit to burn and exhausts the gases. It took me two weeks to do both floors (the furnace is located upstairs). I also installed cold air grills that have a filter rack built in, this help keep the sawdust from being sucked through the return pipes. When it was done I saved approximately $6,000.

[Bob Winkler]

It took me two weeks to do both floors (the furnace is located upstairs). I also installed cold air grills that have a filter rack built in, this help keep the sawdust from being sucked through the return pipes.

Thanks for the great feedback. The cold air return filter rack is a good idea.

I'm especially interested in how you installed it upstairs. Is it a downflow or horizontal flow furnace? How was the ductwork run and are registers at the ceiling or near the floor? Was the ductwork rigid sheetmetal (round or flat) or insulated flexible?

Do you mind sharing the furnace brand name? Sorry for the questions, but I'm sure your experience can help me a lot.

Bob

[Tom Godley]

Much of the online HVAC products are made by Goodman -- Most companies will not sell direct only through distributers. Goodman bought the HVAC division of AMANA a few years ago - the products are different but they do share parts. You will get a lot of discussion regarding relative quality of Goodman.


With large open rooms the need for many smaller ducts runs are reduced -- but I would recommend that you have ducts that cover the doors otherwise you will have uncomfortable drafts. I have also found that having ducts down low that will blow over the slab area will increase comfort dramatically.

The unit can be placed almost anywhere - they are amazingly small. Some units pay a small efficiency price if installed horizontally. Since you are looking at heat and A/C make sure to look at the Heat Pumps -- they are surprisingly efficient even in CT.

If it was me I would not use flex duct - and I would look into setting it up so you can separate the two areas so they can have independent temps. If you go with a high efficiency unit the added cost of variable speed and even zoning is surprisingly little especially DIY. The return filters are a good idea - they are normally used when the furnace is in an attic space and changing the filters is a problem. You will need a filter at every return unless you still provide a primary one and only use the return filters in the shop

But the insulation is the big thing - I have a shop building that 1800sf heated with 30k BTU wall heater. The spray foam changes everything. When I had my addition sprayed last year - The only smell I had came from the OSB they used for the temp partition wall!

[lou sansone]

hi bob
best wishes on your new shop. did you post any photos yet? I have an oil fired forced air furnace that does give me trouble because of the shop dust. in my next shop, I would use gas like you are going to do.

lou

[Zach England]

I have a furnace in my "shop"--it heats the house, though. Yes, I go through a lot of filters.

[Bob Winkler]

hi bob
best wishes on your new shop. did you post any photos yet? I have an oil fired forced air furnace that does give me trouble because of the shop dust. in my next shop, I would use gas like you are going to do.

lou

No fully completed pictures yet as I am working on exterior landscaping and interior finishing work. But here are some from when it was just completed. Current status is that lights and electric are in and some landscaping was finished before the snows came.

Bob

[Charles Murray Ohio]

Bob,

The furnace and AC unit is a Tempstar . I have a Goodman in my house and have had problems. I talked to service people in our area, all agreed that Goodman had a lower upfront cost, but higher maintance costs (2 weeks ago the hot surface igniter, flue collector box and interlock switch had to be replaced on my Goodman).

I used a standard up flow furnace, placed on rubber iso mounts to help prevent noise transfer to the shop below. Because it was centrally located cold air returns were ran into both sides, (filter racks were placed here also, they don’t get changed that often). A cased coil was placed on top, then I made a custom plenum, which ran trunk lines down each side. The location, size and number of returns and supply runs were determined by my friend. I was also able to pick up duct and some fittings (all new) at our local Habitat. Pm me you phone # if you want to talk about this.
Charles

[Bob Winkler]

Thanks for the reply. My HVAC quote was for a Goodman unit and it's good to have some feedback.

I go back and forth between a complete HVAC system vs. wall or console furnace with window A/C. My current thinking is that with extra care and money for excellent insulation, I could simplify the HVAC.

I'm also seriously considering walling off a 10'x24' room in front of the garage doors to use as unheated wood storage. This would help my thermal envelope by eliminating garage door leakage. I could also then add a wood floor over the slab of the now 20'x24 shop.

Decision, decisions!

Bob

[John Davidson]

I did my own HVAC in my shop 3 years ago when I built it. I installed a 2 ton heat pump with electric strip backup. The unit is a Goodman and after all was done I had about $2500 in everything including paying a co-worker $300 that has a HVAC license to sweat the lines, adjust the charge and verify my work. At the time the lowest quote I had was about $5000. The unit has run now for 3 years with no problems. However, I do replace my filters often. I do plan my work and make sure to turn off the unit if I am doing anything that throws a lot of dust into the air. Also, I have a Jet filtration unit to help keep the dust down. I have been very pleased with the Goodman unit.

In fact I have been so pleased that I replaced my home units this last summer with Goodman dual fuel heat pumps. So far they have run great and I am enjoying a major reduction in my heating and cooling cost. Goodman has a bit of a bad rep because in the past they have sold to anyone including DIY home owners. People that are not generally trained to install this equipment are going to have problem unless they have a good support system to help them over any hurdles. There units can still be bought over the internet but Goodman advises against it and will not warranty any unit not sold through a distributor anymore. They are trying to repair the damage that has been done by unqualified installers. I was able to purchase mine through a friend that is a licensed contractor at his cost.

If you have good mechanical and electrical skills with foundational understanding in these areas and a friend that has training in this area it can be a very rewarding project that will save you thousands. On the other hand if you don’t I would not recommend you trying this yourself.

[Dave Beauchesne]

Thanks for the reply. My HVAC quote was for a Goodman unit and it's good to have some feedback.

I go back and forth between a complete HVAC system vs. wall or console furnace with window A/C. My current thinking is that with extra care and money for excellent insulation, I could simplify the HVAC.

I'm also seriously considering walling off a 10'x24' room in front of the garage doors to use as unheated wood storage. This would help my thermal envelope by eliminating garage door leakage. I could also then add a wood floor over the slab of the now 20'x24 shop.

Decision, decisions!

Bob

Bob :

I have been a licensed HVAC kinda guy for 30 years.

While 8 K for what you have quoted is reasonable, proper ductwork is a good chunk of that , I have heard a fair amount of negative about Goodman. That being said, many problems down the road are the result of poor installation techniques. Goodman sells to anyone even up here, and thus, guys not having done their homework do a poor job of installation.

A few points I would consider important:

-Use as little flex as possible on the duct - ASHRAE allows 3 feet max. from the trunk to a register for good design practice. Zero flex is easily done and the best.

-Ensure the duct is designed properly - this is one of the biggest stumbling blocks I see. Cheap out on the duct sizing = problems on both the heating and cooling performance / reliability.

-Have someone who is real competent hook up the A/C - braze with nitrogen ONLY and only buy a R-410a unit - DO NOT allow a R-22 unit to be flogged to you - they work fine, but the R-22 refrigerant is being phased out beginning 2010 -

-Gas installation - ensure someone who is decent does the gas startup - ensure they do a gas pressure test, TEMPERATURE RISE test, and balance the airflow.

-Filter the heck out of the air - the high efficiency furnaces have a secondary recuperator coil that is finned with narrow aluminum fins to capture extra heat out of the condensate - this will plug up quickly with dust.

-Have the first few feet of the discharge and return air plenums insulated on the inside with 1 '' acoustic insulation on the inside - it will be much quieter.

-Ensure the system is hooked up so the combustion air comes from outside ( a 2 pipe system for heating ) .

-Ensure all appropriate permits are pulled - if there are shortcuts taken there, and there is a problem ( heaven forbid a fire ) the Insurance Company will have their way with you.

BTW - I am envious of the shop - enjoy it !! PM me if you have any other questions. There are many options and variables.

Dave Beauchesne
Refrigeration Red Seal Journeyman
' B ' Gas fitter

[Bob Winkler]

Thanks so much for excellent technical information and sound advice. It's always great to have an expert to talk to.