How to Inspect the Heating Systems of Mobile Homes, Double wides, Trailers
MOBILE HOME HEATING - CONTENTS: Mobile home heating system inspection guide
- Common mobile home heating system defects. Mobile home or manufactured home heating ductwork defects. Mobile home insulation defects and remedies to reduce heating costs
POST a QUESTION or READ FAQs about how to troubleshoot & fix problems in manufactured home or mobile home heating systems: furnaces, electric heaters, heat pumps for manufactured homes, mobile homes, trailers, RVs.
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Mobile home heating systems:
How to Inspect the heating systems in mobile homes, trailers, double-wides, multi-wides:
How to spot common and dangerous defects in heating equipment incuding furnaces and boilers, inadequate heat distribution, freeze-ups, and safety hazards.
How to save heating costs for mobile homes and trailers or multi-wides. Page top sketch was provided courtesy of Carson Dunlop Associates, a Toronto engineering, education, and home inspection company.
Hot air, gas-fired, central return heating units are most common ; oil & electric mobile home furnace-heaters are also used;
20% of mobile homes have problems with HVAC (C. r. survey);
[Click to enlarge any image]
Question: I was startled out of my skin to see a cat jump into the living room from a floor vent
(Aug 29, 2012) Maxine Payne said:
The red tag was apparently covered up when vinyl siding was installed. Now I want to sell the property, but I can't because I do not have the red tag number. How do I get the red tag number?
(Aug 29, 2012) Greg Filian said:
The flashing of the lights mentioned are they in the whole house or just one outlet? If it's just one outlet it may be just the outlet, if it's the whole house the problem may be at the main connection.
(Sept 8, 2012) Gail said:
I am looking at buying a double wide through an estate sale. The "trustee" of the estate is the deceased owners daughter, who know very little to anything about mobile homes (as I).
I am hiring an inspector, how ever he wont be available for 3 weeks and I have an immediate concern...
While standing in the living room I was startled out of my skin to see a cat jump into the living room from a floor vent ( vent cover was pulled off) I looked into the vent and it appears to be completley open - no duct work - just a view of the ground beneath. The daughter said that that was common and is there for ventilation. LOL Tell me this isnt so!
Thank you SO much for the wonderful cat - HVAC system question.
Yes I can tell you "it isn't so" - that is, it is not good practice to simply leave floor vents in a home open to the outdoors such that anything, including a cat (or worse, a raccoon) can hop in for a visit.
I can imagine a few reasons why you might have found the missing duct work and open floor vent, all adding up to some more trouble and work for you. For example most likely there was a heating or heating and cooling system that used air but that has disintegrated, been damaged, fallen off, or was simply removed and abandoned.
Sometimes too, when warm or cool air delivery into a home is poor in flow rate or quantity, people try to improve system operation by adding more return air to the system by just cutting an opening that lets outdoor air into the system somewhere. The problem is this is the most expensive possible way to heat or cool a home since it's a "one way" design - we take un-conditioned air from outside, heat it or cool it, then try moving it into the living area.
Really the most significant implication of the cat in the hat, I mean cat in the vent discovery in your possible future home's heating sysem is that it's a red flag to watch out for other work done or "problems solved" by the same person on that home - as you may find other amateur workmanship that lengthens the list of repairs and improvements needed to make the home safe and habitable to normal standards.
Keep me posted, and send along photos if you can (use the CONTACT US link at page bottom or top) - especially if ... the cat comes back.
I suppose a less ridiculous explanation that the owner could have invented might have been to explain
"Oh I forgot to tell you, that's just Marion, my mom's cat. Marion comes with the house. The hole in the floor is her pet door."
Checklist of Common Defects in Mobile Home & Manufactured Home Heating Systems
Air filters are often ignored - change the filter monthly when the heating or cooling system are in use. A clogged air filter will reduce air flow from your heater, increasing heating costs as well as making the home less comfortable.
Outside heating oil tank not protected from freezing (using more expensive kerosene mix?) or use of heating tapes on heating oil lines - a possible fire risk (photo above)
Unsafe heating system chimney and vent installations on mobile homes and trailers (photos above)
Our photo (above left) shows an oil fired heating flue venting directly through the mobile home side wall and just inches from the home's windows.
Our second photo (above-right) shows a makeshift gas flue using aluminum venting (not recommended, unsafe), a too-short chimney (inadequate draft) and flimsy construction, as well as probably leaks into the home wall over the entry door. Notice the soot around the base of the flue where it penetrates the wall?
Unsafe fire clearances and inadequate working space to maintain heating equipment are not due to the mobile home manufacturer but due to low-budget modifications such as this oil burner access through a bath vanity cabinet door (photo above).
Warm air heat return air in a mobile home: all return air taken from crawl area
beneath living unit - one-way heat; blocked return; blocked supply; ducts
through un-heated area;
NO return air, or none when utility closet door is shut! We see this design too often - it is the most expensive way you could heat your mobile home since none of the interior air is being recycled through the heating furnace.
Mobile home heat safety warning: Our photo of a mobile home warm air furnace (left) shows that someone has put paneling over the door to stop drafts - also cutting off return air to the furnace and possibly making it very dangerous if this step has also cut off combustion air from this heater.
Because the mobile home furnace is shoe-horned into a tight space it is too often the case that the system is not inspected and cleaned on schedule. Generally you will save more on reduced heating costs by having an expert clean and tune the system than you will pay for the service call.
LP Tanks, copper gas lines are often left unsupported and exposed to mechanical
damage; also check for LP gas leaks at tanks or fittings;
Oil tanks at trailers and mobile homes - indoor-rated heating oil tanks are quite often placed outside, above ground,
in ground contact, with heat tapes (a fire hazard), often leaking, and in cold
climates, exposed to frost-risk which in turn risks loss of heat and related damage to the home
Missing or still-covered-over spark arrestor on the heating flue on a mobile home - have your heating service technician check the safety of the entire flue and chimney, including the outside components
Combustion Air Defects & Safety Hazards at Doublewide, Mobile Home or Trailer Home Heating System
Below our photographs illustrate several unsafe conditions at a house trailer's heating system inspected by D Friedman & S Vermilye during a mobile home site safety investigation.
No return air from occupied space to the furnace: Above we notice that when the door to the "furnace closet" in this mobile home is shut, there is no return air movement from the home's heated interior to the furnace - creating the most-expensive possible way to operate the furnace. We call this a "one way" heating system: scrounge some air from a cold outdoor or crawl space source, heat it, and blow it into the living space.
In addition to the absence of return air to the heating furnace we notice that
Dirt blockage of air flow: the return air inlet grille is partly blocked by dust and debris, further reducing air flow, increasing heating cost, and ...
Watch out: there is an increased risk of potentially fatal carbon monoxide poisoning if the system lacks adequate combustion air
Blocked air filter: if an air filter is installed (remains to be discovered), given how dirty is the exterior of this furnace the air filter may be equally dirty and airflow blocked
The leak stains and corrosoion on and below the heating flue indicate that the chimney and flue are leaking, risking hidden damage, leaks, holes, water or rust damage to the furnace heat exchanger: all further pointers to an unsafe heating system
On some of these installations combustion air is provided from outdoors through wall or floor openings in the furnace closet, increasing safety but ignoring operating cost
Unsafe chimney outside: incomplete, leaks, missing cap, too short, bad draft - are illustrated by our outdoor heating flue/chimney photos earlier on this page.
Question: Mobile home furnace not working
(Dec 14, 2012) Sean Newcomer said:
I have a brand new thermo pride furnace for my moble home it ran fine for two months the furnace started cylcling, it would burn then the fan would come on after a couple minutes the call to burn would shut off, then the fan would shut off a few mins later, upon fan going off the burner would cycle for heat again and the fan would come on heat would stop and so on. but the heat keeps climbing it doesn't stop
so i got ahold of the installer he told me it was the thermostat, i replaced it and still does the same its under warranty but i can't afford to pay a serve man 200.00 to come to tell me the problem. is it the burner control or is it the computer board can it be reset and how
IF the warm air output from a supply register is blowing right onto the room wall thermostat, then "the thermostat is the problem" could be a correct statement.
Otherwise I suspect a bad fan limit switch or improper installation of that control. For example, if the limit switch is mis-adjusted or if its sensor spring is binding, the system won't work properly.
Watch out: a fan limit switch that is bent, damaged, mis-handled, even mis-adjusted, can be dangerous, risking damage to the heating equipment or even a fire.
Diagnostic articles for heating problem troubleshooting are at
Question: fixing or replacing mobile home or doublewide ductwork invaded by rats
23 January 2015 Chuck said:
I have a doublewide mobile home with the air ducts in the cieling. A rat has gotten into the air duct and chewed insulation and now insulation is blowing through the vent. I am going to have a company put a camera up there to find the break so it can be fixed. My question is would it be easier for me once I knew exactly where the break was to just go in from the roof. It seems alot faster and less expensive than tearing out the cieling and replacing sheetrock, tape and bed and repainting, not to mention the mess in the house. What are your thoughts?
If your doublewide has a conventional continuous metal roof over an inaccessible space then you won't do well trying to cut into the roof and you risk creating a point of future roof leaks. I'd be inclined to work from the interior. But then I haven't seen your home.
If there is an attic access (which some doublewides have) then of course it'd make sense to get into that space and remove and replace the ductwork and any contaminated insulation.
Further, if there were rats in the ductwork, you want to replace ALL of the ductwork and insulation where rats were nesting lest their pee and poop and other debris become a health concern later on.
Mobile Home & Trailer Home Insulation & Ventilation Defects, Diagnosis, Repair, Improvement
Ver4 - 04/25/07, updated through December 2014 - Steve Vermilye, New Paltz NY and Daniel Friedman, Poughkeepsie NY,
Hudson Valley ASHI Chapter Seminar, Newburgh NY, January 4, 2000, NY Metro ASHI Fall 99 Seminar, Holiday Inn Crowne Plaza, White Plains NY, October
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poorly insulated or uninsulated mobile homes have big impact on heating or cooling costs
(Nov 1, 2011) sandra reddick said:
i have a 1996 moble home trailer and was wonder why it is so cold in the winter time a very hot in the summer. just learning that the moble home has no insulation in it,is that a home code violation.
(Jan 14, 2013) Anonymous said:
weird i hv the same problm i hv a 1968 mobl home it is terrible in the cold the summer is unbearable if u hv no ac units.. is it a violation?
"Violation" is a tricky term Sandra and Anon as building code enforcement is ultimately up to local building officials. More confusion can arise because mobile homes, often built by manufacturers who assume their products must comply with building regulations across multiple states or provinces, build to model codes, and local building inspectors, knowing this, may not feel compelled or even able to inspect such homes for local code compliance.
Question: use a residential heating furnace in a manufactured home?
(Jan 30, 2014) Ray Cole said:
Can a house residential furnace be used in a manufactured home
if by manufactured home you mean like modular housing, not a MOBILE home (trailer home) then yes.
If you mean in a trailer home like the types shown in this article - it depends - on equipment size, space requirements, btu requirements etc. The heater must meet the required HUD specifications.
If you have a specific brand and model in question let me know and I'll research the specifics.
Certainly because space and combustion air and btu requirements are often different for a mobile home like the ones discussed here, we expect to see heating equipment designed for safe installation there.
I'd be very wary about just hooking something up without knowing the specifics as you could risk burning the place down or dangerous carbon monoxide hazards.
(Nov 4, 2014) Anonymous said:
to Ray Cole: No you can not use a residential furnace or air handler in a mobile home. mobile homes are under HUD guide lines. In the installation instructions of residential systems spells this out. most heating systems for mobile homes are down flow and Coleman, Intertherm, Mortex make mobile home heating systems.
However, If you decide to replace the system with a package unit they are compatible as long as they have a high static blower system. Mobile home duct systems are not design to maintain pressure the further you get from the source.
Question: some rooms in doublewide don't get adequate heat
(Oct 4, 2014) Kathy said:
I have a double-wide built in 2000, my bedroom and bath are in the back of the house and is always so cold from October through the winter/ spring months. The heater is in great condition and I have had an inspector from the gas company check for heat loss, but it hasn't helped. Could there be a problem under the house with the ventilation pipes and how much would something like that cost to get inspected? I have had electric heaters in those rooms since I bought the place newly built for me. I have also had the company that built the house come out, but I think they only checked the inside.
The least costly first step might be to ask your heating service company to check for a disconnected or blocked heating duct or a closed register or duct damper.
The check needs to include a complete survey of the ducting, including under the unit.
(Nov 4, 2014) Anonymous said:
Kathy, with double wides typically the heater sets on one half of the home and has a crossover duct to the far half. If your cold rooms are on that far half the air flow and temp is greatly reduced by the time it gets to your rooms. the easiest and first step is to regulate the supply grills on the half the heater sets on. Cutting almost off any bathrooms (usually the hottest rooms) if the grills are broke replace them, next regulate to at least half off all rooms closest to the heater.
If this does not get the desired results, I would inspect the cross over duct. It should be dead center of the furnace and at least 12" supply. also you can put a scoop (small piece of metal in those vents in the colder rooms to deflect air up. Lastly I would check the seal around the connection of the floor supply boot to the main trunk line it is where to pieces of metal duct join and reseal with foil tape.
Question: clicking noiser but no heat from my electric air conditioning / heating system
(Dec 13, 2014) Robert said:
I live on a double wide mobile home- have an electric air conditioning/heater system. Couple days ago the heater was working and now it does some click noise like is going to come on but do not come on. What could be the problem? Thanks
It sounds as if you have a heat pump that's not working. See the diagnostics at
If outdoor temperatures are too low for your heat pump to provide heat the problem could be failure of your backup heating system to operate. Look for a control board or relay failure.
Question: Triplewide home does not get enough heat in some rooms
(Mar 13, 2015) Ruth Cameron said:
we have a 1997 triple wide and our issue is that both the back bedroom air don't seem to be have any air or heat coming out and we really don't understand why.rest of house is cool or warm depending on season. we have tried to find blue prints of the duct work thru the manufacturer but have been unsucessful, we really didn't want to go to the expense of someone checking it our and telling us that it all needs to be replaced and that it would be very expensive,can you shed some light on this at all.help is very much appreciated
If you are getting air and heat out of some but not all registers then it's not likely that the heating system itself needs replacement. More likely is that ductwork has come disconnected or become blocked somewhere. On a triple-wide ususally the HVAC ducts are on the underside of the unit. It's worth getting someone with a clear mind and a good flashlight and some knee pads and maybe a helmet to crawl under there to take a look. Not only are you not getting heat in some rooms, but you may be wasting that very heat by blowing it onto the mice under your home.
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 Section 184 Indian Home Loan Guarantee Program, U.S. Department of Housing & Urban Development, web search 1/5/2012, original source: portal.hud.gov/hudportal/HUD?src=/program_offices/public_indian_housing/ih/homeownership/184 - Quoting:
The Section 184 Indian Home Loan Guarantee Program is a home mortgage specifically designed for American Indian and Alaska Native families, Alaska Villages, Tribes, or Tribally Designated Housing Entities. Section 184 loans can be used, both on and off native lands, for new construction, rehabilitation, purchase of an existing home, or refinance.
Also see Freddie Mac & Fannie Mae
 Native American Housing Loan Guarantee Program HUD Section 184 Loans At A Glance, FannieMae, web search 1/5/12, original source: efanniemae.com/sf/mortgageproducts/pdf/section184aag.pdf
 "Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
 New York State: "Manufactured Homes: an installation guide for the code enforcement official," undated. [Div. of Code Enforcement & Admin. - 518-474-4073, George E. Clark, Jr., Director] - this is a guide tool, not an enforcement code or standard.
 HUD State Administrative Agency (for 36 states) (NY: 518-474-4073) - for complaints
 Manufactured Housing Institute, 2101 Wilson Blvd. Ste. 610, Arlington VA 22201 703-558-0400 www.mfghome.org
 NYMHA, 35 Commerce Ave., Albany NY 12206-2015 518-435-9859 800-721-HOME (they want the Star Program to provide for separate assessment of manufactured homes)
 Consumer Reports: www.consumerreports.org - special report 2/98
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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