Central Heating Question

[hsmomx3]

What would be the cause of this?

My cousin has central heating (no gas) and when she turns her heat on above 65 degrees, the entire house smells of sewage. She has had it checked but nobody can tell her what the cause of this is.

Anyone care to take a guess as to the culprit?

[hsmomx3]

Thanks!!

[dirtboy]

Has she changed the air filter in recent memory?

[American_Centurion]

My best guess is that there is a blocked or clogged sewer vent. When the heater's return fan kicks in High the negative pressure is enough to draw fumes back through a sink or toilet trap.

If you smell sewage, always check the traps and vents first.

[hsmomx3]

Not sure but I will ask her. She lives in Sugar Land and I live in AZ.

[Tijeras_Slim]

She bought John Wayne Gacy's old house.

[Tijeras_Slim]

If you smell sewage, always check the traps and vents first.

Nah, blame the dog.

[Cold Heat]

I can't say for sure, but it sounds to me like like it is a plumbing problem. Sewerage gasses may be returning into the house due to the negative pressure created by the air handler intake. The gas (methane) comes up through the drains for the sink, washing machine, and so forth.

There are way to prevent back flows. (back flow preventer)

Consult a plumber.

Other than that, I can't imagine what it could be. Raising the temperature probable causes the air handler to run more, which brings in more gas.

[JRios1968]

Squeaky floorboards

[drjimmy]

Anyone care to take a guess as to the culprit?

[Hegemony Cricket]

If the smell is coming out of the heating vents, I would check the ductwork for the presence of standing water that could have leaked in and gotten stagnant.

If the smell can't truly be traced to the heating vents it may actually be sewage. I would check the plumbing fixture drains (commodes, sinks, shower/bath, etc.).

Good Luck!

[kenth]

LOL... I was just thinking that maybe she needed more lime in the crawlspace.

[Chickensoup]

Another great place for sewage odor to come in is the washer drain.

[Chickensoup]

The solution is to crack a window

[martin_fierro]

Is she logged on?

[Congressman Billybob]

May be dead mice in the ductwork. Human or animal, death has a certain strong sickly-sweet smell.

John / Billybob

[Deguello]

Check the condensation tray for the unit. It may be clogged and the water is now stagnant.

If the unit is ground level, she may have also been experiencing water seepage on the floor. Units in the attic will drip water onto the ceiling (clues that lead to this point).

[Asfarastheeastisfromthewest...]

My cousin has central heating (no gas) and when she turns her heat on above 65 degrees, the entire house smells of sewage.

What do you mean 'central heating (no gas)'? Do you mean that it has an electric element to heat up the air as opposed to gas? Or that heat is supplied from a 'central heating unit' source that services several homes/buildings and she has a smaller unit that she can turn on to draw some heat from that central source as she needs to? And what is the significance of '65 degrees'? Are you saying that with it running below 65 degrees, there is no smell when the heat comes on? There is some missing information here that would be useful to a troubleshooter.

My guess is that some of the posts here that speak about the issue of sewer gas are on the right track..... but they did not go far enough in the explanation. If your cousin has a sink, toilet or more likely a shower in the house that does not get used very often, what can happen is that the u-tube trap in the drain line can dry out. If used regularly, the trap should have water in it - this is what will seal from the back flow of odours and gases up from the sewer. However, if the shower does not get used for a few weeks, the trap may dry out and thus create a ready path for fumes. If this is the case, it means that your cousin's heating unit has the supply and return ducts connected in such a way that the entire house goes under negative pressure when it comes on.... something that it should not do but quite often happens because contractors don't understand the concept of make-up air. [By the way, the same thing could happen if all the bathroom exhaust vents, kitchen range hood exhaust, central vac and so forth are also on at the same time - the house goes to negative pressure since all these devices are exhausting at the same time that no devices are bringing air in to replace what is being taken out... hence house goes slightly negative. This can be a very dangerous situation under some circumstances. If it is a very tight house which allows it to go negative and there ARE gas appliances in the house such as a water heater or a furnace, there is a serious potential for gas fumes to exhaust into the house - trust me on this, more than one person has died of carbon monoxide poisoning with this as the cause.]

[Ben Ficklin]

I suspect the mice also.

It doesn't have to be a dead one either. A build-up of droppings can be obnoxious smelling when heated. Years ago the mice built a nest in my kitchen range and the smell was awful.

[cva66snipe]

Go to all sinks, floor drains, bath tubs, showers, a washing machine drain not used, etc and pour water in the drains to fill the drain traps. A half a pitcher of water is more than enough in most cases. Do so once weekly to seldom used drains. If the traps are empty sewage gas can come up the drain pipe. If the house is on a septic/drain field system the septic tank may need pumping especially if drains become slow.

Signed,
retired Building Maintenance Mechanic with a HVAC background :>}

[cva66snipe]

One more possibility comes to mind but not likely. On newer construction IIRC due to the have materials involved in construction which put off rayon and other gases,. etc. To compensate and meet safety standards newer construction has an intake vent which feeds into the Central heat and Air vent system. This is usually on the roof. There is a very slight chance if the vent was installed too close to a plumbing vent which also vents to the roof it could at a certain temperatures be drawing in sewer gas from the vent. This would especially be possible on manufactured housing where this type of air intake is required.

Next if could possibly be a dead mouse in the ventilation system but that doesn't smell like sewer IMO.

[Cedar]

Since this is a central heating thread.... :)


I try to turn the thermostat down at night to save energy (and money). But this old house has some leaks, and the temperature drops fast inside the house.

So, the unit seems to cut on and off just as many times during the night when it's set on 63 degrees compared to when it's set on 72 degrees during the day.

Seems to me there is no benefit in cutting it down if it's going to run just as much as normal. I might as well leave it on 72 and be comfortable.

Is that right? Any heater guys out there who can answer?

Thanks in advance!

(And just as a side note, I have fixed what leaks I could by adding sealing tape, etc.)

[Snoopers-868th]

I am no expert but we live in an old (over 100) house and one year we went crazy with the caulk and sealed up every crack and crevice. We decided to close off all the upstairs registers. It was a mess. The windows developed condensation and ruined all the trim paint. Some of the caulk on the storm windows has been taken off and I enjoy the cracks and crevices again. We have insulated windows and the house itself is well insulated. That is enough in my opinion. A house has to breathe. Interesting when people were not so concerned about a 'tight' house I don't recall radon being a threat. Wonder if there is a connection?

As far as temp in the house. Where is the thermostat in relation to the heat runs? It makes a difference as to the heat in the entire house. One room might be warmer than the other and if the thermostat is close to a heat run it may not be accurate. We don't go by temp. We go by if we are warm or not and we don't do the up and down thing. We also run the furnace fan continuously.

[Cedar]

Thanks for the comments.

I'm not exactly sure what a heat run is....but the thermostat is in the livingroom, and the furnace is in a utility room (close by but separated by a wall).

The house is a 1950's. I'm renting right now since I might move back to my home state in the next year or two.

So, I'm basically just trying to save on the heat bill and be as warm as possible while saving money (if that can be done??).

It's a small house, and every room gets pretty chilly during the night. As I said, even with the unit set down to 63 degrees, it still cuts on and off many times during the night.

If it's going to do that, I see no cost benefit in cutting it down...might as well leave it on 72. But maybe I'm missing something. I'm sure not knowledgeable about heating units. Just thought I'd try getting the answer here.

If there's no savings, I'd love to leave it on 72! But my mind wants to know FOR SURE that I wouldn't be saving any money by keeping it set at 63... :)

[RetiredArmy]

Dead rat in the system vents maybe. I have seen that before.

[SoothingDave]

I was just thinking that maybe she needed more lime in the crawlspace.

No, you put the lime in the coconut and call me in the morning.

[Cedar]

Still hoping for an answer ping.....

(see post #21 & #23)

[cva66snipe]

It sounds like poor insulation for one thing but here are some considerations. In the day time you have less load on the unit usually due to sunlight and outside temps being warmer. With what you are describing the thermostat may not work as well at 63 and to be honest you save no money going that low. The furnace will have to compensate the next morning to get the temps back up meaning an extended run time. Try 68 and see what happens. That may increase the cycle times. You didn't say what type of furnace or if it's central heat and air etc. If it is a heat pump by all means keep it about 70 at night to let it run longer and cut on and off less frequent.

Here's some advice for people with Central heat and air. Do not close off registers in unused rooms or completely shut off any room. There should be about a 2 inch gap at the bottom of the door for air return on closed doors.

You can damage your unit and shorten it's life doing so especially on the cooling cycle or either cycle on a heat pump. It needs the return circulated air to function properly.

[Cedar]

Thanks so much for answering!

It is central heat and air-conditioning in this house. The landlord has no desire to add more insulation, and you're right...it needs more.

The furnace does have to compensate in the morning--first thing I do when I get up is turn the thermostat back up to 71 or so. I've wondered with all that extended run time in the morning if I was just losing whatever savings I had gained during the night.

I think I'll take your advice and try leaving it at 68 during the night.

From your comments....were you saying that it is better for heat pumps to run longer, but not central heat units?

The man who installed the digital thermostat set it to have a longer run or cycle time (or whatever the term should be) instead of the short one--he specifically said that. Guess he knew what he was doing. The furnace seems to run an awfully long time when it's on, no matter what the thermostat is set on-- the lower or higher degrees alike.

I really appreciate your comments and hope you don't mind answering another question for me. :)

[Cedar]

And by the way...it's a gas furnace.

That's why I'm trying to understand this process -- my gas bill is too high!

[cva66snipe]

From your comments....were you saying that it is better for heat pumps to run longer, but not central heat units? The man who installed the digital thermostat set it to have a longer run or cycle time (or whatever the term should be) instead of the short one--he specifically said that. Guess he knew what he was doing. The furnace seems to run an awfully long time when it's on, no matter what the thermostat is set on-- the lower or higher degrees alike.

The reason you don't want the central air {in the air conditioning mode} or a heat pump in either mode to cycle off and on a lot is due to wear and tear on the compressor motor which is a sealed unit.

I've been out of it for a while but on a house my off the top of my head guess is about $800-$1000 for a 2-3 ton compressor to be replaced. I could be off a few hundred either way but I think that is a low bid. Most problems in electrical motors happen on start up as that is when it is using the highest amperage and under the most stress on the windings.

I saw your next post saying it is gas heat. Cycling off and on too often won't hurt anything in general but the fan motor and relays in that case. It's not yours to worry about though :>}

My guess is you're in a colder climate and your furnace unfortunately for you since you pay the gas bill is trying to heat the great outdoors as well. Here's you a few simple things that don't cost nothing. Daytime winter curtains open. Nights curtains closed as they do have some insulating value. Throw rugs or a towel in front of outside doors to block the air. Keep the filters changed once a month. That is to your benefit. If the air flow is blocked you don't get the right circulation. Sorry I can't help more but if the house is lacking attic insulation {which can be corrected the easiest} it's gonna keep running as heat tends to rise and goes out the ceiling. One good way to kind of tell how good your insulation is serving you is to see how much snow gathers on the roof in say a 3-4 inch snow. If none is laying or it melts off the roof fast within the day you likely have poor insulation.

[Cedar]

Thanks again for taking the time to comment.

I've been changing the filter every 3 months, but since you suggested every 1 month I'll start doing that.

If I owned this house, I would definitely be adding more attic insulation. I think that (plus the 1950's windows--no storm windows at all) are the major leak problems here.

Even if I planned on renting for the next 5 years or so, I'd go ahead and pay for the insulation myself. But as I said, I might be moving next year.

Actually, if I owned the house, I'd put in a woodstove heater. To me, that's the best heat around.

I've been able to keep my electric bill in a pretty good range. But the gas bill has been too high, so thought I'd get good advice on FR.

I really do appreciate your replies!

[cva66snipe]

Glad to do it. BTW if you don't have one get a Carbon Monoxide detector. I've never had a gas furnace myself but I live in the Tennessee Valley and electricity is cheaper.