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YKdave 01-13-2013 07:37 PM

What to do... what to do...
Hello from the great white north! Yellowknife NT to be exact!

not sure if this is the correct section i should post this or not, but ya never know till you take a stab at it!

Brace yourself, this is going to be long winded...

Just bought my first 'home' last fall (first time homeowner, long time renter), its an 1984 "alma" manufactured home. Its had some renovations over the years which includes the roof being re-done as well as the roof in the living room (center of the trailer) has been raised, but neither me or the previous owner know whats been done for insulation. the windows have all been replaced with triple pane lowE w/pvc frames as well as the exterior doors have been replaced with insulated metal and new screen doors. Overall a pretty tight and efficient setup for a 30 year old trailer.

Ive also got a wood fireplace in the living room, which is great because wood comes cheap, but its use is limited to outside temps in the low negative teens. even running the furnace circulating fan and living room temps over 30c, the end rooms struggle to make it to 20c and with any lower outside temps the bellybag starts to cool drastically (floors are f'n cold!), as does the crawlspace (uninsulated skirting). unfortunately, the sewer line from the bathroom runs outside of the bellybag, the full length of the trailer almost, till it hits the main. This line is insulated, but without the furnace being used, it cools off too much under there and the line will freeze eventually. (it needs some better support as it looks to be sagging in places and likely holds water or other goodies :? )

The current furnace is a 1992 nordyne M1GH090, and typical as always to a MH the furnace is a noisy SOB!

As per the usual, the 'normal' operating noise(air movement) of the furnace is a major nuisance as the furnace is located in the hall beside the living room.

I would like to do something about this noise pollution as well as move towards something more efficient.

J load calculation put me right around 26k/btu/hr (using a 60c temp rise) using guesstimate (worst case) values for the roof/wall insulation. using known values, my heat load is actually more like 17k/btu/hr ( average for a month of -20c to -25c outside temp).

ive also come to realize that the current furnace is a bit oversized. Currently its -35c (9km/h wind, -44c windchill) and with the t-stat set to 20c im seeing very consistent 10min/20min (50%)cycle times. even with outside temps dipping down to -40c (almost -60c with the windchill) i still wasnt seeing much more than 55-60% burner time and as much as the weather bites around here, we dont usually get more than a couple days a year where ambient temps are much lower than -40c (without the wind).

This average winter weather puts me around 800-1000L of propane per month (though only 600-800L is used for heating, i have other propane appliances) and at my current contract price of .65/L thats a bit over $400/month in heating

So... all this long winded crap aside...

I would like to do some upgrades over the following summer and im starting to put together a plan for this.

I would like to make the switch to a high eff furnace and keep it gas (propane, as to simplify the install and costs). ive been looking at the nordyne (miller/intertherm or whatever the heck else they want to call themselves these days) M7 series as they are as close to a "drop-in" replacement as a guy is going to get.

What im thinking, is an M7TL060A (possibly buy with a coil cabinet for future a/c because i hate the heat although it doesnt get overly hot here :lol: ). first stage should be more than sufficient to maintain a 20c inside temp during our coldest weather which should make it as efficient as its going to be while running the first stage, and the second stage should have no problem recovering heat loss from open doors/setback temps

My next an biggest concern of the project is the noise!

Ill make the assumption that the M7T is going to be a bit quieter than my current M1G (especially on first stage) but i would like to take it a step farther if at all possible. The biggest issue as usual is the noise at the return air (front panel). would their be much benefit in using a M7 with a top return air and ducting it through the adjacent bedroom closet and have it draw the return air from farther down the hall? (and installing a solid door infront of the furnace which is currently open). or would this make it slightly quieter in the living room, yet resonate and make it even worse for anyone in the bedrooms down that hallway?

Other plans for the summer would include insulating the skirting (R12 fiberglass w/vapor barrier) as well as inspecting the roofs insulation situation and maybe doing something there. Within the next few years the siding will have to be done, its got pretty old wood plank siding, i would like to do some R5 poly on the outside wall for a little extra wall insulation and likely do vinyl siding.

Crunching some numbers, making the switch to the M7T furnace alone should save me at least $70/mo in heating costs as well as some headaches from the noise! then the insulation is only going to compound the savings and hopefully with the crawlspace better insulated i will be able to set back the temps below 20c while i am away and save some heating costs there without having to worry about things freezing up.

So, my biggest concern is the noise, what are my best options for reducing the noise from the furnace and hopefully not just move the noise down the hallway. The ol lady wants to have kids in the near future and neither of us need a screamin banshee every time the furnace kicks in :lol:

jagans 01-13-2013 07:58 PM

Once you have the kids, the "Screamin Banshee" will become a whispering Willow compared to them!


YKdave 01-13-2013 08:49 PM


At that point their would be several screamin banshee's, the furnace, the kid, the wife and me screamin at the works of them to shut up! LOL

old_squid 01-13-2013 10:27 PM

The biggest heating & air conditioning problem with the manufactured homes is the ductwork they have hidden in the floor. Short of opening up the underside of the home, replacing it all and then insulating and making it all tight again it's just something everyone lives with.

Noise as you already know is bad because of the type of return. The new furnace is going to be a bit better but I'm guessing not as quiet as you'd like it to be. Maybe you can find someone that already has that model and visit their house.

Sounds like your wood heat works great, just hard to get the heat distributed throughout the house. The layout of most manufactured homes and how most are setup don't make the options there easy either.

The one setup I did see that worked as best as any (according to the homeowners) was where a package AC unit had been added to the home. The return for this unit was brought into the home high in the living room via the bedroom that shared one of the walls. In most cases these unit just have the return cut in through the floor cause it's easier and cheaper. Not the best place for air conditioning return when all the heat in the summer is sitting at the ceiling. The supply from the AC unit is connected to the existing ductwork for the furnace. This kind of unit sits outside on the ground and has it's own blower. They had set the unit up on a platform and had an insulated cover arrangement they put over it in the winter to save on heat loss. Where the return ductwork goes to the ceiling just needs a little "cosmetic covering" to make it look nicer. The longer run(s) made it a fairly quiet setup.

Just a thought so you have something (else) to think about.

joecaption 01-14-2013 07:11 AM

Sounds like the O/P is a little to far north to be worryed about A/C.
Trying to run lines in the ceiling in a mobil home is out of the question.
Even trying to install ceiling fans would not work because there built so flimsy.
Some pedistal mounted fans with an ossilating feature could get that hot air at the ceiling moving enought to get it to the floor.

COLDIRON 01-14-2013 07:56 AM

You could remove the entire heater and blank off the ductwork then install a self contained heater/AC outside and run the ductwork from the new unit under the trailer and tie into the duct work that way.

Nice and quite and brand new.

YKdave 01-14-2013 08:40 PM

An outdoor unit would be nice, and a headache at the same time LOL

I figure at some point ill have to do something with the trunk, but thats not going to happen right away. if i do tear out the bellybag to do the trunk, it will be after the skirting is insulated and sealed up right.

Moving the return from the hallway alcove to the living room would greatly benefit the use of the wood stove. But, if the new furnace isnt going to be any quieter running on high speed than the one ive got, im nowhere ahead other than possibly using wood heat at lower outdoor temps.

I do understand that the trunk is likely the biggest cause of the noise, but at this time i would like to do everything possible that i can, to reduce the noise without having to do the trunk.

I was thinking, if i do use a top return M7, i could run a return in the hallway as well as one into the living room. as this could be done with minimal work, best case scenario i would also be able to set it to draw ~90% from the end of the hallway normally for minimal noise in the living room, and be able to draw 100% return from the living room while using the wood stove. with any luck, it should be alot more efficient at moving the heat out of the living room, so i may be able to get away with a lower fan speed.

Doc Holliday 01-14-2013 08:57 PM

is it the motor or the noise of the return air being pulled into the grill and thus into the system that's making the noise? manufactured home system come not specific to one size but more three sizes. You can simply lower the blower speed of the motor to push/suction less air. They do this to accommodate the partnered condenser unit which is not a three in one, but only one size and that size has to match (well, at least for optimal efficiency of the complete system) the air speed of the inside blower. The bigger the outside condenser, the higher the fan speed. Lowering the fan speed will reduce efficiency but not enough to financially evict you from home over the course of a year.

look on the wiring diagram.

if it's the motor than that can be upgraded to a much quieter and more efficient x13. Google.

YKdave 01-15-2013 07:14 PM

it is the air movement noise, the furnace itself although getting old runs like a champ.

Unfortunately, its a single speed fan, and the unit being oversized BTU wise, is likely a higher CFM fan than the original. Unfortunately i dont know what the original unit was that was installed from the factory.

Their is the option of buying the factory 3spd fan, but its hard to justify dropping that kind of cash on a 15 year old furnace that the exchanger is probably going to fall apart in a few years LOL, all in hopes that a lower CFM is going to make a big difference in sound. the fan installed is a 10x8 rated at 1100cfm, nothing extraordinary, especially compared to the M7 which the med/low speed is similar in CFM.

Of course, the lower fan speeds arent much use if the furnace is firing, but may be extremely beneficial for circulating air while using the wood stove without it sounding like a tornado ripping through the house LOL

Doc Holliday 01-15-2013 07:34 PM

Is this similar to your set up?

sammy37 01-15-2013 08:48 PM

Im all for package units on mobile homes. Seen many and all with great results, plus it frees up a space in the home for a new pantry/closet.:thumbsup:

YKdave 01-15-2013 09:08 PM

same color LOL

Really nothing like what ive got. the current unit is an M1GH, typical low end low eff downflow gas furnace.

Heat pump is out of the question, mostly due to our winter temperatures typically sitting at the bottom scale of their operating range not counting the several weeks of -45/-50c we see! and power is a bytch, at ~$.30kw/h and power prices going higher in the next few years, it bad enough i have to run the circulating fan LOL

YKdave 01-15-2013 09:21 PM

ive crunched alot of numbers and propane is going to be my cheapest (as far as running costs, not to mention the upfit will be cheapest) and best route to go.

The only other option, that would give me the lowest running costs would be to go with a wood pellet boiler. which brings in a whole new set of its own issues. including the fact that i would have to use an exchanger to still use the existing forced air system to keep the bellybag and crawlspace at a decent temp in the winter to avoid freezing up the pipes! and payoff would likely be a LONG ways down the road, as install cost would be much more compared to keeping the forced air gas furnace, not to mention im still stuck with dealing with the circulating fan noise :(

the numbers i have came up with:

80%eff propane averages $416/mo (what i currently have)
90%eff propane ~$369/mo (save $50/mo)
95%eff propane ~$346/mo (save $70/mo, plus possible power savings)

78%eff pellet stove ~$364/mo (save $52/mo, but have to run circulating fan and likely not be able to use it half of the winter)
88%eff pellet boiler ~$322/mo (save $93/mo, but again still running the circ fan and alot higher install cost)

80%eff oil furnace, out of the question, but would cost an extra $169/mo in fuel over propane

Now, keep in mind, we do have a rather long heating season (typically the furnace is only turned off may-sept LOL). so any cost savings, adds up real fast

COLDIRON 01-16-2013 05:03 AM

Seems like your awfully worried about the belly bag, don't worry about it nobody here has mentioned anything about the belly bag except you.
If your really interested in the proper way to attack this here's what you should do this summer.
Install a high eff furnace sized properly, move the sewer line and all water sources under the trailer, insulate and skirt the entire exterior of the trailer.
And don't worry about the trunk line. Do it.
OH! and put a remote digital thermometer under the trailer near the sewer line so you can monitor the temperature inside the skirting.
Live with the noise until Summer.

creeper 01-16-2013 05:20 AM

Something else to think about.

You will save on your Hydro bill with the 95% one. You will see the savings, especially if the power goes out and you are stuck using a generator for a while. You can hook that beast up and still have a furnace.

Down here in muggy south/central Ontario, from may/oct I keep the fan running constantly on my 95%. It sucks the cool air up from the basement and keeps the place nice and comfortable. I don't even notice it on my Hydro bill.

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