- just replace it and wait another 20 years
- go tankless
- go solar
Just Replace it:
this option was the cheapest but I had concerns about the amount of gas it used, the fact that the water heater and furnace and stove shared the same gas pipe, and the size of it. It was wedged in a closet by my front door so I couldn't go bigger without relocating the water heater anyway. This is probably the biggest reason why I didn't go this route. to flat out replace it on the cheap I was looking at $1k if I did it myself (which I would have to learn how to do as I went along). Had a pro come out and he quoted me ~$2k to do it right. However, if I wanted a bigger water heater relocated in the garage, then we were talking ~$2500-$3k. If I went for one of those super efficiant 80+ water heaters I was looking at ~$4,500k.
I thought this was the way I would go. However when I looked into it there were some problems. First, the most efficiant tankless water heater is electric. However, for a growing family of 4, I would need something that took a lot of amps of electricity. My home service is 100amp, but an electric was going require me to go to 200amp. someday I would like to do that but not today. So electric is out which leaves me with gas.
Gas is less efficiant (80-88% is what my research seemed to indicate) and it takes A LOT of gas to flash heat 4gpm of water. Tankless water heaters are rated by how much water they can heat with a given flow. My shower I messured at 2 galons per min. I have 2 showers and a dishwasher. In the winter, it can get down to the low 40's for a daytime high. so I need to be able to heat water up about 60-70 degrees @ 4 galons per min. all the units I looked at were in the 180,000 BTU range; that's a lot of BTU, much more then what my regular water heater, furnace and stove would all take at the same time.
When I had the professional come out to price one out, it turned out to be about what I expected. I would have to put the tankless right off the side of my gas service with 3/4 pipe and run lines to it through the garage. This was already at ~$4,500 and there was the possibility that it would cost more if I had to get an earthquake valve and permits. Finally, there was a chance that it could cost me more per month as I had found post from people who had gone this route only to find out that because of the high BTU needed to flash the water they used more gas in the winter then previous to installing a tankless. When I did the math comparing say 1 hour of use flashing the water with a 180,000 BTU tankless vs. say 6 hours of gas use on a traditional water heater; this seemed to make some since to me.
Solar Water Heater
I initially did not think that I would go this route, but the more I looked into it the more I liked it. I was thinking that we wouldn't get hot water during the night with a system like this, but that turned out not to be true...
There are many different types of solar water heaters but they break out into 2 basic types: passive and active.
Passive solar water heaters have no pumps and heat water directly. some systems have tanks up on the roof (usually painted black). The positive is that there are few, if any moving parts. the negative is that since it uses water directly, that water can freeze in cold weather.
Active systems use pumps and some kind of radiator fluid (like glycol). the glycol, in this case, runs through pipes in the panels, heats up, and is pumped into an heat exchanger in a water heater. Active systems won't freeze, but they have more moving parts which could break.
Solar hot water systems seem to cost a lot more then traditional or tankless systems. The system I liked would cost a little over double what a tankless would. Needless to say, I had to go back through my PGE bills and try to figure out how much gas I used for hot water heating though out a year; then amortorize that over the next few years to see if this system would pay for itself (figuring about 5% increase in gas cost per year). Still that cost came out to paying itself off in 10 years (best case) and 17 year (worst case). I'll post that excel doc (once I can find it). All this being said, I kept having this naging feeling that Natural Gas prices would go up higher then 5% on average of the next 10 years (I guess time will tell), but if it goes up say an average of 8% year over year, this system could pay for itself in 8 years.
The solar water heating system I went with is from a company called Velux and the integrators were a local company called the Solar Connection . Actually we were told that we were the first house in america to get this system (they seem to be big in Europe). The down side was that the water heater died in early March and this new system wasn't available until April; we waited and heated a lot of water on our stove.
I chose them because I wanted freeze protection, I liked the look of their mostly flat panels, and the hot water heater comes with a built in electric tankless backup which didn't require a service upgrade to my house (this is your failsafe so that you always have hot water). Since this was the first install in the US, it was also the first install for the integrators so it could have gone smoother, but they did their best to take care of me and I appreciated that they took their time instead of rushing it; I was happy with the final result. they also installed a solar tube in our permanently dark, kitchen which I justified as an offset to the electricity which the glycol pump would use (@ 90 watts per hour when it's running).
There's been a few times I've second guessed myself about putting down so much money on hot water heating, but I think in the end it will pay for itself and increase the value of the house.