I am thinking about replacing my 20 YO Waterfurnace

[Jerry_NJ]

My 4 ton 20 YO Waterfurnace geo(ground source) heat pump has cost a few thousand in repairs over the last 5 years and on the repair (about $400 - and a great service/dealer, glad I met him) this winter I asked about replacing the two speed compressor. He said, it is no longer available... and how much longer will it last??? Wh knows? Well its time for a scroll compressor anyway.

He gave me a rough $10K estimate to replace making use of my existing loop and pumps (which were replaced 3 years ago) and using the 30% tax rebate.

The new unit may give me upwards of 5 for a COP, I now get 4. Cooling would also be more efficient and he thinks the two speed compressor, which cost less, is the proven compressor. The variable speed will give a slight improvement in efficiency - but it is yet to establish a "track record"...e.g., my existing two speed (not a scroll) has lasted 20 years.

I've got my fingers crossed the existing compressor holds for the rest of this unusually cold NJ winter FedEx cancelled deliveries yesterday due to weather (mainly driveways I think as roads are fully open) because of weather. I know because I was scheduled for a delivery of a new "toy"... a Crosman , not a Waterfurnace : )

 

[Circus]

If it ain't broke don't fix it. I would focus on a temporary emergency heat source so if it does die you'll have time to think about your options.

 

[Jerry_NJ]

I hear-ya, and think that is about what I am doing...but thinking making a replacement before the failure comes, and it will. My wife isn't very patient when it comes to TOO COLD or TOO HOT, and a working HP is what that's all about.

Given the existing unit cost me about $9k (I got about $3K from my power company) and I have put about $5K into repairs in the last 5 years I have a total investment of about $14K. So that could be considered a $700 depreciation per year. If I also consider I didn't spend $200 a year on routine maintenance for an oil burning my cost is closer to $500 per year.

Now if I take into account my savings in energy cost, again compared to oil, for the last several years, lets say 5, I saved at least $1K a year in heating energy cost...likely more (what's oil now $4 per gal?) or not only paid off the investment I made a net profit (or got a return on my investment).. Or said another way, the unit paid for itself just counting the past 5 years. To this I can add the savings over oil for the previous 15 years were I assume the difference to oil was less than $1K a year, closer to $500. So, really I made a profit off the old "girl".

Hope I didn't count anything twice, just doing this economic analysis as I type (typo).

As I said, I am holding back fire wood just in case the HP fails, or the electricity fails - either or both could happen before spring. If nothing fails I win again, as I'll not disappoint my wife. We've been married 53 years this month....it doesn't get easier with time : (

 

[Circus]

Everytime I've tried to be proactive I've regreted it. Comes down to not really knowing what's apt to fail or finding that the replacement was less reliable. Congrats on 53 years.

 

[Jerry_NJ]

I guess there is no way to know the condition of a compressor (bearings and seals would be failure points I will guess) without tearing it down.

One thing is for sure 20 years is a long time for a compressor to be in service. This is a two speed so the start/stop count is increased by the fact the controller switches back to stage one as soon as it can (most efficient speed, but lower heating capacity) and if it can't hold the temp, it switches back to stage two. It does these speed changes by stopping and then restartng in the different stage/speed. This increased the number of off/on cycles I believe and know that is the main source of wear. Too, the design was set to run a lot, the system is very quiet and the most uniform heat/cooling is accomplished when the unit runs a lot. I have no run meter information, but if it runs just 12 hours a day for 200 days a year, we'd accumulate 2,400 hours per year and 48,000 hours in 20 years.

Translating that estimate to something I have experience with, think about an automobile engine running at 40 mph for 48.000 hours, that would be almost 2 million miles... how many engines would that take? I'm not suggesting any direct relationship between run-time on one verses the other, but.. 48,000 hours is a lot of running and bearing friction on the original factory grease.

 

[woodgeek]

Yeah, but its an electric motor, not an IC. Running a lot cooler too. Basically a glorified Frigidaire.

The calculation I would do is say its averages 3 ton, 36,000 BTU/hr * 50,000 = 1.8 Billion BTUs delivered, same as about 200 tons of cordwood burned in a woodstove. Envision your house filled 5' deep in cordwood.

 

[Jerry_NJ]

Interesting parallel... but I don't remember what a cord of well seasoned hardwood weighs.. I think it contains about 15 million BTU. Working from that recollection and estimating it would take at least 6 cords of seasoned hardwood to heat my home for one season I get 90 million BTU, or 1.8 Billion BTU needed for 20 years, hey I get the same number starting from a different point and with an estimate (6 cords) I find this quite interesting. But the compressor also cools, not as much as it heats but maybe 1/2 as much or another 900 million BTUs in 20 years. So, how much wear and tear does the equivalent of 9 cords per year, 180 cords in 20 years account for in terms of compressor wear. I think it is about worn out. This is my original premise for "time to replace".

 

[woodgeek]

hard to say....waterfurnace have any info? Air handler in good shape?

 

[Jerry_NJ]

On a repair a couple of months back I talked with the repair/installer/owner and he didn't have any forecast on the compressor. He was there because the compressor quit working, but the problem was electrical, not mechanical. He replaced one or more capacitors and maybe some other minor electrical components. He had everything he needed to repair on his truck. He also recharged the ground loop...he was working with a clear understanding of this old machine, which he said goes back to the days he entered the business. He knew were everything was and didn't need to consult any repair manuals. He also said he had more confidence in the two speed compressor in the new units, rather than the variable speed, which also cost more.

He may have said something about the air handler life, but I don't recall. There must be some rust from de-humidification and the heat exchanger must have some "hard core" dirt reducing its efficiency - it has never been vacuumed thoroughly. All-in-all $10K sounds like it is competitive with just a few major repairs.. and I end up with a completely new and "better" (??) unit One thing for sure my compressor isn't of the scroll design and thus an inferior unit even if it were new, or could be replaced with a new. If I could get a new retro-fit scroll compressor and new heat exchanger (handler) for under $5K I might go for it. But remember, there is a 30% rebate on a new system, nothing on a repair.

My main concern isn't the cost of replacement, more it is will the economic advantage survive the "war n coal" and the "electric rates will necessarily skyrocket" mentality in Washington. If electric rates double the advantage of the heat pump could evaporate.

 

[woodgeek]

The 30% rebate drives the decision. The air handler has logged a lot of hours, the heat exchanger could be pretty gunked/corroded (although it is dry in heating mode). I suppose the plan is to check the expiry of the rebate (and your elegibility) and plan on buying a new system shortly before that. And if you were comfortable with a 2-speed, no need to change (unless they are not sold any more).

Politics aside, you are already in an expensive elec market. I am having a hard time seeing how your elec prices could double given the current low price of natgas, and low penetration of wind power. Both of those (and to a lesser extent PV) would look very profitable in a 2X elec cost scenario. I know the quote in question regards a C-tax, but (i) that is not in the cards in the US and (ii) if it were implemented, it would be at such a low value as to 'nudge' the market in a desired direction, not to explode it.

 

[Circus]

Doubt the comparison is valid but my fridge ran fifty years. Ran fine but finally replaced it cause the cabinet insulation was soaked.

 

[maple1]

Do you know what your monthly operating costs are?

(How much electricity does it use?)

 

[sloeffle]

I have the 5 series furnace that you are talking about upgrading to. I have had it for about 3 years now and have had no issues. I do get my pressures checked yearly. I would recommend the variable speed ECM motor vs the PSC motor. DC motors are built to last a lot longer

http://www.thomasnet.com/articles/machinery-tools-supplies/ECM-Motors-HVAC-Systems

My furnace uses 22amps on stage 1 while running measured via amp clamp. That equates out to 5280 watts and hour of electric usage. According to the Waterfurnace documentation my COP is 4 since I am using a ground loop. Yours should be higher since you have a ground water loop vs a ground loop.

Here is the series 5 specifications:

http://www.waterfurnace.com/literature/5series/SC2500AN.pdf

 

[woodgeek]

I have the 5 series furnace that you are talking about upgrading to. I have had it for about 3 years now and have had no issues. I do get my pressures checked yearly. I would recommend the variable speed ECM motor vs the PSC motor. DC motors are built to last a lot longer

http://www.thomasnet.com/articles/machinery-tools-supplies/ECM-Motors-HVAC-Systems

My furnace uses 22amps on stage 1 while running measured via amp clamp. That equates out to 5280 watts and hour of electric usage. According to the Waterfurnace documentation my COP is 4 since I am using a ground loop. Yours should be higher since you have a ground water loop vs a ground loop.

Here is the series 5 specifications:

http://www.waterfurnace.com/literature/5series/SC2500AN.pdf

Does the 22A include the loop pump?

 

[maple1]

I have the 5 series furnace that you are talking about upgrading to. I have had it for about 3 years now and have had no issues. I do get my pressures checked yearly. I would recommend the variable speed ECM motor vs the PSC motor. DC motors are built to last a lot longer

http://www.thomasnet.com/articles/machinery-tools-supplies/ECM-Motors-HVAC-Systems

My furnace uses 22amps on stage 1 while running measured via amp clamp. That equates out to 5280 watts and hour of electric usage. According to the Waterfurnace documentation my COP is 4 since I am using a ground loop. Yours should be higher since you have a ground water loop vs a ground loop.

Here is the series 5 specifications:

http://www.waterfurnace.com/literature/5series/SC2500AN.pdf

How much would it run in a 'typical' winter day - or say average per day over the winter?

I did consider Geo before I redid my boiler system - I couldn't get any kind of good handle on what I could expect for electricity use though. People I knew with recent installs were pretty fuzzy in their answers - which I interpreted as 'more than I thought I would'.

If I assume the 22 amps you mention, and further assume it would be running half the time, that would work out to around $10/day in electricity for me. I have no idea on runtime though, that's just a WAG.

 

[sloeffle]

Does the 22A include the loop pump?

Yes, the 22 amps is running both pumps and the furnace.

How much would it run in a 'typical' winter day - or say average per day over the winter?

I did consider Geo before I redid my boiler system - I couldn't get any kind of good handle on what I could expect for electricity use though. People I knew with recent installs were pretty fuzzy in their answers - which I interpreted as 'more than I thought I would'.

If I assume the 22 amps you mention, and further assume it would be running half the time, that would work out to around $10/day in electricity for me. I have no idea on runtime though, that's just a WAG.

I cannot give you a good idea on how much the furnace runs during the winter because I try to run my wood burning furnace when temps are <30F. I also do not have any electricity usage logging setup. That is on my to do list. My house is all electric, two adults, one child and we generally use around 1400KWH during the spring and fall when the furnace runs the most.

The furnace that I have is 4 tons. So on first stage I am heating / cooling the house with 2 tons of heating or cooling. Like Jerry eluded to, the furnace is setup to run for long periods of time to keep the temperature swings to a minimum and to also increase the life of the equipment. During the summer time our KWH usage decreases because the geo unit makes hot water for free via the desuperheater.

I am glad with the decision that I made. The Trane propane furnace / air source heat pump that I was looking at was about the same amount of money. The geo unit shines in the summer time compared to an outside AC unit. Plus I do not have to listen to an outside condenser unit run while I am trying to sleep.