skip to main content

Heating & Air Conditioning

Old dial mercury thermostat question

3 years ago

I have a Trane natural gas furnace.
If I set the thermostat below 68 degrees, the furnace begins to cycle and I hear it ignite but then it shuts down before fan blows if I keep it at 70 it operates fine with no issues.
It's a very old dial type mercury thermostat. Is this just the thermostat causing this?

Sort by:Oldest

Comments (3)

Elmer J Fudd
3 years ago
If it seems to be not working normally and it's also old, aren't those two good reasons to replace it?
mike_home
3 years ago
Are you able to remove the cover on the thermostat? If so then you should be able to see the mercury bulb. The mercury moves inside the a clear bulb to make a connection between two contacts.

If the mercury is making contact then the furnace should turn on and stay on until the mercury slides back and opens the connection between the contacts. If the furnace stops running while the mercury is still connecting the two contacts, then it is a furnace problem.

If the furnace starts and then stops quickly and the mercury has opened the contacts prematurely, then its a thermostat problem. A simple check is to see if the thermostat is level.
Related Professionals
Poplar Bluff General Contractors · Georgetown General Contractors · Fort Dodge General Contractors · Lafayette General Contractors · Wheeling General Contractors · Saint George General Contractors · Carbondale Home Remodeling · Southaven Home Remodeling · Pittsburgh Home Remodeling · Dothan Bathroom Remodelers · Houma Bathroom Remodelers · Lafayette Bathroom Remodelers · Hilton Head Island Bathroom Remodelers · Middletown Bathroom Remodelers · New Bedford Bathroom Remodelers
HU-867564120
3 years ago
Decrease the anticipator setting in the thermostat.

Related Stories

FLOORS Is Radiant Heating or Cooling Right for You?

By Mariana Pickering (Emu Building Science)

Questions to ask before you go for one of these temperature systems in your floors or walls (yes, walls)

KITCHEN DESIGN A Cook’s 6 Tips for Buying Kitchen Appliances

By Christine Tusher

An avid home chef answers tricky questions about choosing the right oven, stovetop, vent hood and more

BATHROOM DESIGN How to Settle on a Shower Bench

By By Any Design Ltd.

We help a Houzz user ask all the right questions for designing a stylish, practical and safe shower bench

REMODELING GUIDES Why Marble Might Be Wrong for Your Bathroom

By By Any Design Ltd.

You love its beauty and instant high-quality appeal, but bathroom marble has its drawbacks. Here's what to know before you buy

BATHROOM DESIGN A Designer Shares Her Master-Bathroom Wish List

By Jennifer Ott Design

She's planning her own renovation and daydreaming about what to include. What amenities are must-haves in your remodel or new build?

GREAT HOME PROJECTS How to Add a Radiant Heat System

By Mariana Pickering (Emu Building Science)

Enjoy comfy, consistent temperatures and maybe even energy savings with hydronic heating and cooling

KITCHEN DESIGN Standouts From the 2014 Kitchen & Bath Industry Show

By Ventana Construction LLC

Check out the latest and greatest in sinks, ovens, countertop materials and more

HOUSEKEEPING How to Clean Your Range and Oven

By Bonnie McCarthy

Experts serve up advice on caring for these kitchen appliances, which work extra hard during the holidays

LIFE You Showed Us: 20 Nutty Home Fixes

By Becky Harris

We made the call for your Band-Aid solutions around the house, and you delivered. Here's how you are making what's broken work again

HOME TECH The Future of Home Automation: Cheap, Wearable and Mobile!

Look for smart watches and glasses that can control your smart-phone apps, which in turn automate your home equipment

Sponsored

More Discussions

Trane or daiken II

125

MUA design for possible Accurex hood (opaone inspired)

11

Replace central oil system or go with entire house ductless?

18

Portable Air Conditioning

4

HVAC for condo unit that limits access to outside drainage

6