dslreports logo
site
 
    All Forums Hot Topics Gallery
spc

spacer




how-to block ads


Search Topic:
uniqs
18896
share rss forum feed


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside

Furnace runs a lot

I am in NY. It is 50 outside and I set the thermostat to 62. Seems the furnace will turn on every 10 or 15 minutes. That seems excessive for such a small difference in temperatures.

Trane 90 efficiency furnace. I'm on my phone posting this so I'll post model number later, or check an older thread where I mentioned it. Thermostat is a programmable one which seems fancy but I just set it to 62 and hold.

House is 1300 sq ft and it was built 1924 so insulation is poor or non-existent. Nothing in attic or even basement (when I got cable installed they ran the cable wire right down the wall from the second floor to the basement so I know there isn't insulation at the top of the ceiling in the basement either.

Someone said they can put insulation there for $150 labor but I don't know if it is worth it.

Even in a poorly insulated house, with a temperature difference of only 12 degrees, how often should it be turning off and on? It's only mid-October for crying out loud.

The other day it was set to 62 and I went to shut off the system on the thermostat. It took a few minutes to shut off. Normally it goes off after a couple of seconds if I shut it off. Ideas?

I had everything looked at and cleaned last month, so the person didn't see any problems. Although I wasn't using the furnace then since it was still warm out.


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside

3 edits


Furnace is 2 stage if that matters.

Waited around for exact timing. Seems like clockwork, it will be off for 20 minutes, then run for 6 minutes and then shut off for 20 minutes then run for 6 and so on. Not sure if that could explain something.

Everyone I talk to says they set their thermostat to 62 when they leave and 68 when they're home (give or take a degree). This seems like a waste to be turning on all the time if I leave it on 62 when I am not home. The digital thermostat shows the inside temp never really changes. It will stay on 62. I have just left it on 62 whether I am here or not.

Bobcat79
Premium
join:2001-02-04
My thermostat was calling for a lot of short cycles, which I found annoying and figured was bad for the furnace. So I set it to the 'hot water' setting to get longer cycles.

I don't know if this would be good for your furnace or not (2 stage and all that).

GroovyPhoenx

join:2006-05-22
Gloucester, ON
reply to fartness
Last time my frunace did that I changed the filter, seemed to have cleared up a lot of issues.

Guess it wasn't pulling in enough air or something but changing the filter improved the performance 100%

instead of starting like clock work it would start when it got cold etc like it normally should.

MaynardKrebs
Heave Steve, for the good of the country
Premium
join:2009-06-17
kudos:4
reply to fartness
said by fartness:

House is 1300 sq ft and it was built 1924 so insulation is poor or non-existent. Nothing in attic or even basement (when I got cable installed they ran the cable wire right down the wall from the second floor to the basement so I know there isn't insulation at the top of the ceiling in the basement either.

Someone said they can put insulation there for $150 labor but I don't know if it is worth it.

Spend the money on the insulation. R40+ in the attic first because that's where it's easiest to insulate and gives you the most bang for your buck. Couple of hours to blow R40+ up there. Next do your basement if the foundation walls are exposed, R14 min. - preferably R20.

Finally do the main/2nd floor walls if you can. If your house is wood frame construction, cellulose insulation can be blown into the stud cavities either from inside the house or the outside - there will be minor wall repairs required to do this.

With your 90% efficient furnace, 10% of your fuel money is going out the furnace exhaust - about 70% of your money is going to heat the outdoors because you have no insulation. Only about 20% of your money is actually keeping you warm.

Spend that 70% of your annual heating bill on installing insulation now on the attic and basement insulation before you hit the really cold weather. Tackle the side walls when you can afford it.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to fartness
said by fartness:

Everyone I talk to says they set their thermostat to 62 when they leave and 68 when they're home (give or take a degree). This seems like a waste to be turning on all the time if I leave it on 62 when I am not home. The digital thermostat shows the inside temp never really changes. It will stay on 62. I have just left it on 62 whether I am here or not.
Of course... Other people use a setback of few degrees, but they also keep the house warmer. So it takes a while for the house to cool down.
Keep in mind that energy use is proportional to IN-OUT temperature difference and the temperature inside is just a number that has no value in a discussion unless you specify the outside temperature.
For reference I set my thermostat at 69F while home, 45F (basically off) while away (never gets that cold anyway so the units never start). The system calculates the start time to reach 69F by the time I get home.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to MaynardKrebs
said by MaynardKrebs:

With your 90% efficient furnace, 10% of your fuel money is going out the furnace exhaust - about 70% of your money is going to heat the outdoors because you have no insulation. Only about 20% of your money is actually keeping you warm.
As a matter of fact 10% goes out the flue and the rest 90% is heating the outdoors anyway

WVBill

join:2008-07-04
Summit Point, WV
reply to fartness
I have a similar problem

There used to be an "Anticipator" setting on manual thermostats that you could set to allow the temp to "overshoot" you set-point by a couple degrees on the high side, - effectively making a set-point "range" and reducing the number of cycles.

I can't find the same setting in the new electronic thermostats, so as soon as my temp drops below my set-point it calls for heat and as soon as it hits the set-point it shuts off - - making for a very short cycle and a very short time between cycles.

Where's the anticipator setting on the electronic thermostats?


Zupper
Premium
join:2002-12-28
Novelty, OH
Are you sure it is actually calling for heat? Or is it just cycling the blower? I think some thermostats have a setting for cycling the blower, for additional filtration and attempting to keep the temperature even throughout the house.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to fartness
said by fartness:

Even in a poorly insulated house, with a temperature difference of only 12 degrees, how often should it be turning off and on? It's only mid-October for crying out loud.
How often is irrelevant in the absence of the BTU rating.
Expect R-values of 3.5 for walls and 2.5 for ceiling.
If your 1300sqft is a rectangle ranch 45ftx30ft (comes to 1350sqft, close enough) you have 1300sqft of ceiling and 1200sqft of walls.
Your losses will be 1300*12/2.5=6240BTU/h for ceiling and 1200*12/3.5=4114BTU/h for walls. Disregarding the floor for now as the basement is likely to stay warmer than outside. Add window/door/draft losses and you're likely looking at 12,000BTU/h *GUESSTIMATE*
How much will the furnace cycle? If it's 50,000BTU/h for stage 1 then it should run roughly 25%. 6 minutes run/20min pause means 23% duty cycle, pretty damn close.
The good part is that you'll be able to keep a 50F in-out differential on that stage with 100% duty cycle on that stage.

Bobcat79
Premium
join:2001-02-04
reply to WVBill
My Honeywell thermostat has a "fuel" setting. It can be set for electric, gas hot air, or hot water (but not steam). I have gas hot air. They say if the cycle times are too short on the hot air setting, to switch it to hot water.

Mine used to turn on for 30 seconds(!) at a time, which was ridiculous. So I switched it to hot water, and it works much better. It can sometimes take 2 or 3 minutes from adjusting the temperature until the heat comes on, however.

Weird thing is that it also affects the cycles on the cooling setting. I guess they used the same algorithm.


rex0

join:2002-02-10
reply to fartness
Going to at least r40 in your attic is money well spent. It's a 1 day project, inexpensive and easy to do. You're literally throwing away money without proper insulation.Ny is zone 6 so it would be even better to go r50-r60. Read »www.ornl.gov/sci/roofs+walls/ins···_01.html for more information there's even a calculator you can customize to your location, gas prices and insulation prices.

What kind of thermostat do you have? do you know if it's setup correctly.

Assuming your furnace is setup correctly don't worry about the cycles. Newer furnaces are designed to run longer at lower output to save energy and keep your home more comfortable.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to fartness
Calculate the ROI and payoff time before anything. Attic insulation *will* help and will likely pay off soon if you take into account the energy tax credit (costs roughly $1/sqft so ~$1300, minus 30% tax credit=> some $900 net cost).
You get some 90,000BTU/$ if I remember well. Average temperature Nov1-Mar1 (120 days) for upstate NY seems to be in the 35F range, say 25F in-out difference. Ceiling heat loss will then be (1300*25/2.5)*24*120=37,440,000BTU, at 90,000BTU/$ comes to $416. Now imagine you could cut it by a factor of 10 by having some decent insulation -> new cost $41. Also savings in the summer for the A/C... so expect a payoff in under 2 years. Spending significantly more for much better insulation will likely take a *very long* time to pay off since you're only dealing with (maybe) $100/yr losses.


rex0

join:2002-02-10

1 edit
Agreed you don't need to go crazy with spray foam, huge R values. It also depends on how long you're planning on living here. If this is a long term home then going R-50 or 60 you have plenty of time for a pay off. Sticking to the recommended minimums you can do this project for not much money at all:

Cellulose is between $8-$10 a bag most stores give you a free blower rental. Pack of baffles for your vents (if you have vented sofits is about $20) You're probably looking at about 57 bags (but check whichever brand they're selling locally the bag/website will have information on how to calculate bags needed) for R-38 in a 1000 sqft attic ~$460 for the attic insulation maybe $50 more if you wanted to go R-42. Add maybe $10 for a pair of safety glasses and some dust masks if you don't have any. Including summer you could even be looking at just over a year to pay for itself, not to mention you'll be much more comfortable.

The other thing is check a couple insulation contractors. When I was increasing my insulation I found a company that did it for less then what it would have cost for diy using the same materials and I didn't have to crawl around in the attic.

Gimmered
Premium
join:2005-02-26
Mccook, NE
reply to fartness
You really need to get some insulation. Your house shouldn't be dropping to 62° with a 50° outdoor temperature.

You should also expect a furnace to short cycle more during mild temperatures, but it shouldn't need to run as often.

gregz

join:2009-10-01
reply to fartness
Download the Heat Load calculator at »www.hvac.cc/ It will give you a idea of what your Heat Loss is.


rawgerz
The hell was that?
Premium
join:2004-10-03
Grove City, PA
reply to fartness
Didn't see windows mentioned. If they are single pane glass, that would cost a lot. If you plan on having new siding done in the near future, also have a house wrap installed.
--

You can't make all the people happy all of the time. But it should be common sense to shoot for the majority.


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside

1 edit
reply to fartness
I looked on the google and it seems some furnaces are set to cycle 3 times in an hour which is what mine seems to be doing since it is like clockwork and turning off for 20 minutes, then turning back on for 6. It's always exact. It's like a setting.

I see I used 1.5 therm on my gas meter since 24 hours ago. That's a waste when I wasn't even home all day and had it set to 62. It was 50 out all day.

Is $150 a fair price for the basement to be done? Seems kind of high since the person said it will take 2 guys maybe 1 or 2 hours. I can run a wire from the upper floors to the basement through the walls and have it come out in the basement ceiling. There is no insulation if I go to the walls in the basement and look up.

How much should the attic cost?

Most of my windows are new. For the older ones, I bought that plastic stuff to put on them to minimize loss. Will it make a difference if I put it on the new windows too? They are vinyl replacement windows. Maybe $100 windows. I just bought one and it didn't even qualify for the energy star credit.


rex0

join:2002-02-10

1 edit
It should still only cycle if there's a call for heat. It sounds like you're losing so much heat it has to heat. There are settings for cycles per hour some some are set in the thermostat others in the furnace. I'm sure one of the hvac guys can give you more information but it probably wouldn't hurt to either bring in a hvac contractor or look at the instructions for furnace and thermostat.

See my post above for attic insulation prices break down. Probably somewhere in the $450-$600 range to do the attic.

What are they insulating in the basement? walls, ceiling, etc. Installing batt insulation is easy if that's all they're doing I'd be inclined to save the $150 and do it myself in a few hours.

edit: don't forget about air sealing around doors, windows, protrusions etc. A $5 investment in caulk can really cut down on air infiltration.


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside
They would probably put the bags of insulation in the basement ceiling space that leads to the other floors.

Where do I put caulk and what kind? Any good videos to watch? Not really sure what to search for.


rex0

join:2002-02-10
Caulk is really secondary after insulation. Why fill in the small holes when you still have an enormous one in the roof. Basically there shouldn't be gaps around window frames, door frames, light fixtures, hose bibs, dryer vents, etc. A good quality silicone (like GE) or solvent cure acrylic is the way to go. There's good information here »www.energystar.gov/index.cfm?c=h···_sealing. There are some videos on youtube »www.youtube.com/results?search_q···+windows


AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1
reply to fartness
If the house is unoccupied, set it to 50 deg in this weather when you are out.
--
standard disclaimers apply.


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside
reply to fartness
I left the heat off all day. It's 45 outside right now. The temperature inside shows 61. That makes no sense that the heat would sense it needs to be on if it was 50 outside and I had it set to 62. It seems like there should be a setting or something that would make it run when it needs to run, and not every 20 minutes.

gregz

join:2009-10-01
Ever have a HVAC tech come in and look over the system to make sure everything is up to snuff? If you have a electronic thermostat, make sure that the batteries have been replaced, especially if you do not not know how old they were when you moved in.

Right now my thermostat says that it is 69 in here, the thermometer on my desk says: 68 inside first floor, 66 in the basement, 50 in the attic space, with a outdoor temp of 44 outside. This is with a house with no insulation in the walls, only in the bathroom, but the attic has blown in up to six inches deep, and rim joists have R-13 in them.

My house in pretty weather-tight, with good door seals, door sweeps, double pane windows with storms, and good storm doors. You have to look at it as a pro-active approach, as in "What can I do to save money by sealing the house from outside weather, but not too tight that it does not breathe.

Also, if you have bathroom fans, put a flapper on the duct for it, that closes when not running, so that you are not leaching warm air through that vent, same as making sure that the drier vent is also in good working order.


mix

join:2002-03-19
Utica, MI
reply to fartness
When your furnace is on, how long does it run for? There should be a setting on your thermostat for the cycle length if it is a fancy one. Better yet, find or download your manual.


toby
Troy Mcclure

join:2001-11-13
Portland, OR
reply to fartness
said by fartness:

I left the heat off all day. It's 45 outside right now. The temperature inside shows 61. That makes no sense that the heat would sense it needs to be on if it was 50 outside and I had it set to 62. It seems like there should be a setting or something that would make it run when it needs to run, and not every 20 minutes.
The new thermostats learn and anticipate the future need of heat/cool. Over time they learn what your house is like and how it acts over the different seasons.

If your furnace is running, its usually because it needs to. Is the thermostat actual temp more than a degree F above the commanded temp? Is warm air coming out of the vents.

Before fixing the insulation, fix the air gaps under doors, around light switches, power sockets. If you have a fireplace, block it up or install a wood stove insert.

If you leave the heat off in the winter to save a few dollars, you can end up with a bigger bill to replace all your plumbing (and house interior) because of frozen pipes.


fartness
computersoc dot com
Premium
join:2003-03-25
Look Outside
Will the outside temperature have to be 32 for them to freeze?


toby
Troy Mcclure

join:2001-11-13
Portland, OR

1 edit
said by fartness:

Will the outside temperature have to be 32 for them to freeze?
Depends on several things. It might be colder in parts of the house than outside, or there might be a delay in the house heating up in the morning.

Having a furnace run, even at 50 deg F, will help stop pipes freezing around the house. In very cold places where pipes can freeze within hours of having no heat, its important to keep the house heated to an ok temperature. This is because you lose power and its already 50 deg F, it can drop fast to dangerously cold levels.

I would work on fixing any air gaps around the house, you might need to replace door seals, a cheap fix.

This item might be worth buying, it will really show you where the problems are. »www.amazon.com/gp/product/B001LM···TC21231D


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to fartness
FIY I've had pipes freezing with 60-65F inside in an apartment with crappy insulation.


AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1
said by cowboyro:

FIY I've had pipes freezing with 60-65F inside in an apartment with crappy insulation.
What was the temperature outside?
--
standard disclaimers apply.