[dannieboiz]

Been trying to figure out my high NG usage. We went on vacation for a few days recently and turned off our HVAC. The only NG appliance running was our hot water heater which used 1.04 therms just to stay hot. It's on the to do list to be replaced.

We usage an average of 6 therms a day this past month to keep our house @ 68 for most of the day and 70 for about 6 hours a day. Cost us about $350 a month in NG which is IMO ridiculous. According to PG&E comparable homes uses 60% less energy than we do. The only thing that's NG is Hot water heater and HVAC

It's been a relatively cold year here in NorCal. It's our 2nd winter in this house and it was very similar last year. Our old house was only a few hundred sq smaller and our NG never exceed $200.

Our furnace is at least 20 years old so it's not anything efficient but was wondering if a new system can reduce the usage by 25-50%?

 

[user_12345a]

If your current furnace has a continuously burning pilot and open draft hood, replacement with a 90%+ model will save a fair bit.

But be warned, a high efficiency furnace won't cure the problem.

If you have air ducts in an attic, that's a potential huge loss especially if there's an issue like deteriorating ducts, leakage.

 

[dannieboiz]

Thanks, I was quoted by a costco rep in the nieghborhood of $16k for a new Furnance and A/C then resealing my vents if there are any leaks. I had to be crazy to agree to that. A furnace and A/C unit should be no more than $4-5k, 10k for labor is a rip off imo

I'm also exploring having new insulation blown into our walls. I think part of my other problem is a non insulated floors and our crawl space is extremely cold. I know this cause our water pipe is down there and whenever we turn on the water it's freezing at first until the hot water gets to the faucet.

 

[Bud9051]

Hi Dannie,
Let's look at your numbers. You say the water heater used 1 therm while you were on vacation for a few days. If a few days was 7, then that water heater would be using over 4 therms per month, that's huge. Maybe that needs to be moved up on the list.

I was trying to give you a savings number for moving from 85% to 95% with your furnace, but I first must subtract your water heater from your yearly use. See if you can tune in on what that water heater is using.

Bud

 

[SeniorSitizen]

It may save as much as 15 percent in fuel but after a 10 year period I suspect you'll be in the hole from maintenance cost. Read the hundreds of posts of problems with HE products and you may come to the same conclusion. You'll need to read between the lines on maintenance cost because contractors on this site don't like for that being discussed.

Invest in insulation, prevent air infiltration and you'll be ahead of the game.

 

[user_12345a]

I'm also exploring having new insulation blown into our walls. I think part of my other problem is a non insulated floors and our crawl space is extremely cold. I know this cause our water pipe is down there and whenever we turn on the water it's freezing at first until the hot water gets to the faucet.

You have to do some diagnostics and see where you're losing heat. You likely have multiple issues, especially if the house is old.

For a crawl space you need to encapsulate it, air seal and insulate the walls, not the floor. If your ducts are in the crawl space doing that would save far more than putting a high efficiency furnace.

You need to fix the house before putting in new hvac stuff. When you fix the house you need a smaller furnace and ac, otherwise comfort suffers.

It may save as much as 15 percent in fuel but after a 10 year period I suspect you'll be in the hole from maintenance cost. Read the hundreds of posts of problems with HE products and you may come to the same conclusion.

Up to 30% if going from natural draft and the furnace may need to be changed anyhow.

Basic condensing furnaces aren't any more expensive to repair than mid efficiency ones. Same controls and motors. You get into high repair costs when you go for equipment with ecm motors, modulating gas valves, communicating t-stats.

 

[Daniel Holzman]

I do not understand your cost figures. You say you use 6 therms per day average, which is 180 therms per month. According to https://www.google.com/?gws_rd=ssl#q=cost+per+therm+in+san+francisco the cost in San Francisco averaged $1.23 per therm, so that would be about $215 per month, but you say you paid $350 per month. Either your figures are off, or you are paying 50% more per therm than the quoted average, which may be worth investigating.

 

[beenthere]

So how big is your house.

Is the duct work also in the crawlspace.

 

[Bud9051]

Thanks Daniel H, my bad and your numbers help. If we assume a monthly use of 150 therms for heating for 6 months and an 85% furnace (20 years is not that old) then 0.85 x 150 x 6 = 765 therms of actual heat. (That's 150 per month for 6 months or 900 therms but 135 went up the chimney and only 765 went into your house.) Divide the 765 by 0.95 for the assumed new efficiency and you get 805 therms, the new amount you would need to buy for heat. That means you would have saved 95 therms with the higher efficiency furnace. Plug in some real numbers and the results will be similar, a coupl of hundred dollars per year savings at best.

Bottom line is, your current furnace isn't doing that bad and the improvements you need will come from improving the house. The irony is, the more you improve the house, the less you would benefit from a new furnace.

There are online programs where you can do your own energy audit to help identify the best places to make those improvements.

Bud

 

[dannieboiz]

Sat down and firmed up the numbers. Hopefully this can help you guys help me..

The house is almost 2300 Sq ft two stories built maybe 1980 zillow shows 1999 which i know isn't accurate but neighbors home range between 1978 to 1983

Downstairs duct work is in crawl space. I like the idea of encapsulating it, I've been down there many time to run my data cables and it's cramped. Most areas are maybe 15" tall at the very most and certain areas I can only fit my arm through. There are multiple vents under the crawl space as well. I assume this is to allow moisture to escape? If I encapsulate it I guess the vents will not be needed anymore since it will be pretty sealed off from exterior moisture?

The vent ducts are insulated and all looks good in the crawl space. I had all the upstairs duct replaced with insulated ones when we first move in cause our electrician flatten a bunch of them.

Here's the exact usages between Dec 16 to Jan 1 the figures in bold are the days that we were on vacation. left column is the date and right column is the therm used. As you can see, on the 29th is the day when HVAC was off for 24 hours straight and we used 1.04 therms. That's pretty high too right?



16 7.3
17 7.3
18 5.21
19 6.25
20 6.25
21 5.19
22 3.11
23 7.26
24 9.34
25 9.34
26 9.34
27 10.37
28 3.12 (this is between midnight to 10am when we shut off HVAC leave)
29 1.04 (Heater off all day)
30 7.27 (Turned heater on while we were at the airport at noon. The house was 55 degrees when we turn it on set to 68 degrees)
31 8.31
1 9.35
avg 6.785294118 a day

 

[roughneck]

First, worry about the building envelope. Do any and all insulating you want to do, then worry about the hvac. If you do it reversed, you'll find yourself with an oversized furnace when the home is tightened up.

 

[gregzoll]

Yes if your furnace is 20 years old and the Water Heater is old, both have never been checked for any kind of gas leaks, yes you will see high charges.

I would not trust a Costco rep, farther than you can toss them. Those rep's are paid by third party companies to sell stuff, but have no idea about how the equipment works or how to size it properly for your home.

Where you live, you could probably get by with just a Heat Pump and a Air Handler with aux. heat strips. As for your Water Heater, they really do not get that efficient over all of this time. They have improved the insulation on them, so that it is foam instead of Fiberglass. I have a power vent water heater and compared to the standing pilot, our bill went down big time for Natural Gas, along with keeping the Thermostat at 66, and having new siding installed on our house with a foam backer core, has helped to keep the house warm.

If that $350 includes all utilities that PG&E delivers (electric, Gas), then yes it can be high. Also because of prices, every part of the country is different in what they charge for NG. I am with Ameren. Even though our prices are going up a bit this year, it will still come down to being lower than any other NG supplier.

PG&E has always been higher than any other supplier. You are paying three times as much as I do with Ameren.

Depending on which rate plan you are on, it may be worth rechecking if a different plan will lower your costs. You may want to start looking at alternative suppliers for Electric & NG, instead of staying with PG&E. Your PUC has all of the information you need in finding a cheaper supplier. http://www.cpuc.ca.gov/PUC/energy/Gas/natgasandCA.htm

 

[gregzoll]

Dannieboiz you need to stop shutting the furnace off at night. Just leave it for a lower temp setting. I have mine set at 66 24/7. My furnace may only run three times max a day.

I have a Lennox Signature Series Furnace, which has paid off. You would probably be best to go with a Heat Pump and Aux heater strips if Electric is cheaper than gas.

 

[dannieboiz]

Since this is a DIY forum, would insulating the home be consider a DIY job? What are my options?

Blowing cellulose in the attic seems fairly easy but I see foam type sprays they do in walls which I really like the look of as it seems much cleaner.

 

[dannieboiz]

Yes if your furnace is 20 years old and the Water Heater is old, both have never been checked for any kind of gas leaks, yes you will see high charges.

I would not trust a Costco rep, farther than you can toss them. Those rep's are paid by third party companies to sell stuff, but have no idea about how the equipment works or how to size it properly for your home.

Where you live, you could probably get by with just a Heat Pump and a Air Handler with aux. heat strips. As for your Water Heater, they really do not get that efficient over all of this time. They have improved the insulation on them, so that it is foam instead of Fiberglass. I have a power vent water heater and compared to the standing pilot, our bill went down big time for Natural Gas, along with keeping the Thermostat at 66, and having new siding installed on our house with a foam backer core, has helped to keep the house warm.

If that $350 includes all utilities that PG&E delivers (electric, Gas), then yes it can be high. Also because of prices, every part of the country is different in what they charge for NG. I am with Ameren. Even though our prices are going up a bit this year, it will still come down to being lower than any other NG supplier.

PG&E has always been higher than any other supplier. You are paying three times as much as I do with Ameren.

Depending on which rate plan you are on, it may be worth rechecking if a different plan will lower your costs. You may want to start looking at alternative suppliers for Electric & NG, instead of staying with PG&E. Your PUC has all of the information you need in finding a cheaper supplier. http://www.cpuc.ca.gov/PUC/energy/Gas/natgasandCA.htm

350 would be the high side for just gas. I say 250 is about average of my gas. My electricity used to be about 200 to 250 but I just got 7.28kw PV installed last month which on my calculation covers almost 100% of my annual electricity usage. Hence I'm concentrating on natural gas now.

I'm looking at a Rheem XG50T12DU36U0 which is the most EI unit available for my area. I live in a county that requires an Ultra Low NOx unit so I'm pretty limited to which gas water I can use. A tankless water heater won't work for me since I use a a recirculating pump for instant hot water

 

[gregzoll]

Since this is a DIY forum, would insulating the home be consider a DIY job? What are my options?

Blowing cellulose in the attic seems fairly easy but I see foam type sprays they do in walls which I really like the look of as it seems much cleaner.

It would be up to you. I would stay away from the retro-foaming, because it does not always get into all voids in the insulation in the walls.

Do like I did to start off. Seal all air leaks around the outlets with the DAP foam in a can and the insulated pieces that go between the outlet and the plate. For the windows, you will have to remove any casings around the inside area of the window, in order to also foam around them. The doors I would use the Z retro weather stripping that is on an aluminum channel, if you currently have issues with the doors leaking. It looks like the newer style insulation used on doors, but it works really great in air sealing.

As for the attic and walls, it is again what would you gain if a company that does the Air leak test first, then insulates and then does another air leak test, so that they can calculate the credits that you will receive and the difference is what you pay.

I never did get our outside walls insulated before the siding went up, which is Alside's Prodigy line. I do still have at least 6" of insulation in my attic, and the house has never had any problems with heat loss up into the attic.

Turning off the furnace at night and back on, will cause your bill to rise, because the furnace has to run longer to get the air up past Dew Point and also to dry out any humidity that has built up from the cooling of the house.

Start with the looking of alternative suppliers if the alternative plans with PG&E do not work for you. At the same time look for a reputable company that will stand behind its work, and will supply you with references. You may even want to check with neighbors who have had new units installed.

It was an over a period of five years that it took us to get the formula right and bring our heating and cooling bills way down.

 

[roughneck]

For when you replace equipment, here's some reading material

http://www.angieslist.com/articles/difference-between-best-hvac-brands.htm
http://efficientcomfort.net/documents/Understanding_HVAC_System_Design_Issues.pdf
http://efficientcomfort.net/documents/Sizing_&_Selecting_for_Proper_Humidity_Control.pdf
http://efficientcomfort.net/documents/Bigger_is_Not_Better-Sizing_Air_Conditioners_Properly.pdf

Get away from big box stores, and hire someone that has your best interests in mind. HVAC is a puzzle. Put it together wrong and efficiency, capacity and airflow ratings given from the manufacturer don't mean anything. Your systems only as good as it was installed.

 

[gregzoll]

Also I would probably go with a Zoned system, so that you only need to heat those zones at the higher temps to help balance out the temperature in the whole house, when you are in them or not. Using a thermostat that you can control from your computer, tablet or smartphone works wonders.

 

[user_12345a]

1. Zoning is totally, totally unnecessary with two systems.

2. A 20 year old furnace won't be 85% efficiency. If it's literally 20, it will be 80% or 90%+ rated, with actual efficiency varying if not tuned properly.

Metal pipe, no pilot, induced draft = 78-80%
Standing pilot, metal exhaust, draft hood = 60-65% Have spark ignition and it may even near 70%. pre-1992
plastic exhaust = 90%+

=============================
About the crawlspace:

1. The vents must be closed and sealed off, otherwise insulating and encapsulating is a waste of money. You will have to provide some piped combustion air to the furnace, water heater.

The moisture comes from the soil, foundation, and air leakage.

The moisture entering will be greatly reduced. You may need to operate a dehumidifier down there in the summer to control moisture depending on the climate, but the cost of running one (maybe 500-1500kwh per year of electricity) will be offset by much reduced heating and cooling costs from doing this.

When you have no floor insulation or vapour barrier the crawlspace is like a basement; leaving the vents open is like leaving a window open in a finished basement.

For insulation rigid foam is really good, but check local codes- it may need to be covered by something fireproof. Fiberglass with vapour barrier on the warm side i'm not fond of in a basement because it traps moisture from the foundation in the insulation. Double vapour barrier it and any moisture that gets into the insulation may never get it.

There's also roxul board.

==========================
As far as insulating the walls goes, a 1980s house should really have at least r11 as is. with blown in cellulose you must be careful; it must be done by skilled pros using the "dense pack" method. otherwise it will settle and you may get condensate in the wall.

without the vapour barrier, air moves though loose fill insulation. insulate the wall like that and the cold side will get colder, cause condensation and rot.

the dense packing stops the air movement, makes for a much tighter house. not perfect.

Law of diminishing returns applies to insulation. If you have R20+ in the attic, the money will be better spend elsewhere - crawlspace first, attic ducts second, then look at air sealing, insulating walls if there's nothing.

HVAC equipment last. Going from a working 80% efficient furnace to 95% isn't worth it.

===========================
Can you post any climate information? The gas consumption sounds like what you would get where i am in january with a well insulated house of the same size.

If you're well above freezing, boy, you've got some really serious problems to deal with.

 

[dannieboiz]

Wow that's a crap load to read. I'm in San Jose, California, so we're already paying the weather tax, well above freezing for sure.

I would say we average in the 50's low 60's between Nov to Feb.

All the windows and sliding doors has been replaced with double pane. Entry door already have the weather strips. I do have my gas fireplace vents open but it's fully enclosed with glass doors and they're kept closed when not in use. I did some work on one of my wall when we moved in and had part of the drywall removed to run wires and the insulation was a 4" fiberglass insulation which is pretty typical around here.

The homes here are tract homes and it's hard to believe that my neighbor is using 60% less energy than I am in "older" condition.

BTW: I just got off the phone with a local insulation company, it's $1.50/sqft of wall rough guess, I might have 1800 sq ft worth about $3k just for the walls. lain: