Very Different Furnace Porposals

[Lancaster 16]

We must replace our old oil furnace with a new, hot-air gas furnace.

We have four widely different proposals. They vary from a 115K Goodman to twinned 80K Carrier Infinity Series. Prices go from about $x for a Bryant 3 stage 355CAV060120, to nearly $x for 2 Rheems RGRL 07EMEAS furnaces, to $x for the Goodman 2 stage 115K, up to about $x for the 2 Carrier 58MVC 80K units. These include filter cabinets, piping, duct work, removal of a large old furnace and of two 275 gallon oil tanks.

Guesses about the proper size of the furnace vary from a bit over 100K to 160K. The wide range worries me.

Part of the difficulty in estimating the proper size of the furnace is the house. It was built in 1815 with 20" limestone walls and has mostly original windows. Despite a lot of recent work, there are still plenty of air leaks. And the building is big, 40' by 50'. It is two and a half story, with duct work running to the 1st and 2nd floors. It has a full basement and a finished attic that is 50' by 22', usually unheated, but with baseboard heat when needed and some insulation.

Another difficulty in estimating how much furnace we need is that we live on the 2nd floor and the 1st is used for storing antiques and books for a part-time business. We have cut the dampers to the 1st floor almost completely off and send the heat to the 2nd.

I no longer trust the chimney that was used for the existing furnace. I have to be able to exhaust out of a hole for a cellar window. I believe this requires a 95+% furnace, which would qualify for the $1500 tax credit.

We are in our 70s and will have to relinquish the property within the next decade or so. We are sweater people during the winter and don't expect any 70 degrees, but the next owners may not be. I am looking for a more flexible solution than our first proposal of a 115K, if 2 stage furnace. We want what we do to be useful to the next owners. They are likely to be commercial--this will be encouraged by the village planning. The village we live in is a bit outside Lancaster, PA.

Finally, the offer that seems the best value--the 2 Rheems furnaces--is by a one-man shop, operating out of his house. He is a Ruud distributor, involved in HAVC for many years, and has good references for his recent work, but he has been on his own only since 2007. Can one man properly service the installation? If a Rheem distributor has to take over, will they be resentful we didn't buy from them? Is warranty work paid for by the manufacturer?

Any advice will by very much appreciated. I've never bought a furnace before.

[sktn77a]

Sounds like a two unit system will better meet your needs. Can't comment on anything else other than the warranty question: none of the manufacturers include labor in their warranty - parts are covered but the labor warranty is an additional installer charge. It's hard to tell who will be in business in 5-10 years, large or small.

[jrbenny]

Pricing questions are not permitted here.

Thank you.

[heaterman]

I hope you have natural gas and are not going the LP route. There are several sidewall vent kits on the market that allow for side wall venting of oil furnaces so that may be an option for you, we use them all the time. We did a Civil War era home a few years back that is on the same lines as what you have. 24" solid brick walls with orignal shash. You will need an experienced contractor to handle this install and wild guesses at what your equipment needs are can be costly for you. Calculating heat loss is going to be important for you if you want a reasonable level of comfort now and especially in the future when it comes time to sell. You most likely will be best served with a two unit setup but start with a contractor who can actually figure your heat loss and airflow needs, not just guess at it.

[fixitguy]

A basic place to start, is what was the heater size of the oil equipment.

what was the nozzle size 75,000 btus? thats a comparsion start anyway.
I'd think it would be difficult to figure the heat loss of 24" walls...

Yes 2 systems would be fine. One guy, since hes got good local refs should be OK. Its just 2 single family homes at one location!! Attic install for the 2nd floor; and basement for the main floor. Im sure he gets a helper if he needs one.
seems hes been doing this awhile.

Any money "saved" should be spent on more insulation and plugging up the fresh air leaks. Insulation pays back ALL THE TIME, heat or cold weather 24/7.

Please give us a report back when its working!
thanks

[BaldLoonie]

Be nice to get an accurate load calc done so the guessing is out of the picture. 1 big furnace could do it but won't know until it is accurately crunched. If you need twins, staging them will greatly increase comfort & efficiency and a smart installer would have no trouble doing that.

NOW, it is generally a problem to twin variable speed equipment. The Carrier & Bryant dealers are quoting that way so I hope their equipment is an exception to the rule. I glanced at their instructions and saw no approval of twinning. Anybody know for sure?

The RGRL is a great furnace and can easily be twinned and staged. Parts warranties are by the mfr. and labor from the dealer. Some dealers won't warranty a part on a furnace they don't install however. We do, we want you as a customer.

80% furnaces sidewall vented require a power exhaust kit which is pricey & noisy. They can't just stick a metal pipe out the side wall of the cellar. I'd stay with the 90+ models that side vent with plastic pipe.

[heaterman]

Just as a starting point the R value of limestone will fall between 0.108 and 0.114 per inch (depends on sample used) and the K value (thermal conductivity) will fall between 1.26 and 1.33 per inch.

[Rdy2Zone]

Look for a poster within this site name "beenthere" and privatley ask him to hop in his horse drawn buggy and provide you with what you need. He's a Moderator on this site and from Lancaster. I would use him, but I dont think he travels to NJ.

[WhoIsThat?]

We must replace our old oil furnace

How old?

If you do a dotplot of the bids

...a....bcd..e....f
0.....|.....|.....|.....
relative price..$

do the bids cluster together?

In the example, a & f are outliers and the true cost for doing the job in your zipcode today is probably c or d.

[Lancaster 16]

Thanks to everyone for the advice.

Sorry about the mention of price--I wasn't seeking advice on that, just using it to illustrate how different the bids are: the highest is almost double the price of the low bid.

My old furnace was about 40 years old and it's dead. They will be running a natural gas line to the property shortly. The old duct work will be used. There are two branches, one going to the 1st and 2nd floors in the front (southern exposure) of the building and the other to both floors in back.

If we do put in two furnaces, rather than twinning, I probably would ask that they operate independently, with the front one responding to a thermostat in the current location on the first floor and the other feeding the back ducts and responding to a new thermostat in the back bedroom. When a cold north wind hits the back of the house, it turns the stone very chilly.

Does "staging" a furnace refer to the fact that all these models are 2 or 3 stage? Are these particularly difficult to set up properly?

I believe that the proposals are based on 1) this is the the biggest 95% furnace this brand has or 2) the old furnace was 200,000 BTUs and supposedly 75% AFUE measured at the stack.

I have seen talk of Manual J for calculating the heating load. I assume this would be very difficult to do on my place--at least, no one has volunteered. We have so much stuff around (we've gone to far too many Lancaster County auctions), you can't get at most of the windows from the inside. Incidentally, our ceilings are 9' and 8' 4", if anyone likes to do calculations.

If one does a rough calculation of 50' X 40' = 2000 X 2 = 4000 X 60 for a fairly drafty house you come out with 240,000 BTUs. No one has proposed more than 160K.

I understand that putting in the right size furnace is important. Would the flexibility of having two 2-stage furnaces with variable blowers make it possible overcome this difficulty of not being able to determine exactly what is needed?

I will try to contact "beenthere". Thanks to all.

[beenthere]

If your current furnace is 200,000BTU's, you won't need a larger twinned combination.

Twinning VS blowers can cause trouble.


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