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CHOOSING WATER HEATERS See also: QUE VEUX DIRE
"MIXING VALVE"? TriangleTube Water Heaters. My plumber (Winters Plumbing and Heating, Belmont) uses water heaters
from some outfit which sells directly to contractors. "A.O. Smith", I
_think_; I can trot down to the basement this weekend and let you know.
It's possible that Winters would resell them to you, but they're not really
in the retail business. Murray's Plumbing Supply in Medford is a "purveyor to the trade". There's also Metropolitan Pipe right in East Cambridge, not sure if they have water heaters but they had a fitting I needed for the car (and amb thinks he has some exotic parts in his slaab). The Gas company sells water heaters too. I'd recommend asking a good plumber or two, like Hank and Rusty, for manufacturer recommendations. I've seen several A.O. Smith water heaters barely live out their 10-year warranties, but that may be better than average. I've buried a few of those, they seem popular. The gas water heater in my house died right before we signed the P&S and was replaced under warranty with an identical unit -- can't recall the make but I'll check if you want. *Don't* get a Rheem direct-vent unit unless Phil has time to design a better controller for it. There was a water-heater article in Fine Homebuilding a while ago ... hmm, www.taunton.com/fh/ to the rescue! "REPLACING A WATER HEATER", by Peter Hemp, Oct/Nov 97, #112. "By making a few simple upgrades, you can triple a basic water heater's life expectancy" (I've got this one, somewhere) FHB had some other intriguing-looking articles, check the index at that
site. Conventional vs. Tankless: My hot water heater has died, so I'm evaluating alternatives. I need to do this quickly; Hank will probably be here tomorrow to install the replacement. He spent today replacing the gas line in the basement, as he smelled gas when he was here to pronounce the old heater dead, and found a small gas leak. (There was a small gas odor in the basement before I bought the house, but I had the gas company look at it before I closed, and they claimed nothing was wrong. It's probably been leaking slowly all this time. If someone knows of a way to pry the money for the repair loose from the gas company or someone else, please let me know.) Anyway, I need to decide between a 50 gallon tank and a Bosch Instantaneous heater, and I want to call Hank tonight and tell him which I want. Does anybody have any experience or comments about the Bosch? I've always used tank systems, and the idea of infinite hot water certainly appeals to me. --Marc We have a tankless system in our current house (not a Bosch) and I personally loathe the thing. What "tankless" means is that the only way water gets hot is if it passes through your heater (or an adjoining flame). That means the source has to be hot enough to heat the water. Which means turning on or turning up the heat and potentially heating your whole frikkin house every time you want to take a hot shower. Bleah. It's a lose, imnvho. --Alan I've seen two kinds of 'tankless' heaters. I suspect the Bosch is an on-demand type that shuts down when water isn't needed. It's a dedicated unit that does nothing but heat water. They might be okay; they're used to good effect in commercial settings like hotels and dorms. I (and probably wex) have a "tankless coil" in the home-heating boiler. This requires the boiler to be maintained at something like 150 degrees all year long. Heat. Waste. OTOH, infinite hot water is nice. I don't have to worry about running out with a houseful of guests, dishwashers and laundry. But I do have to worry about pressure. I don't have balancers, and the coil has gotten very calcified over the years. The result is that I get a max flow of about 1.5 gpm straight hot water, and if anybody touches a hot tap elsewhere the showerer gets extra encouragement to wake up real fast. --dca Tankless and instantaneous do not seem to be the same thing. Tankless is where you have a hot water resevoir for a hot water or steam heating system, and that is used to heat the hot water. This sounds like what you have. Instantanous is where you have gas which heats the cold water directly into hot water; it is completely separate from the heating system. I have forced hot air, so I can't have a tankless system. --Marc >What "tankless" means is that the only way water gets hot is if it passes through your heater (or an adjoining flame). That means the source has to be hot enough to heat the water. Which means turning on or turning up the heat and potentially heating your whole frikkin house every time you want to take a hot shower. That is -certainly- not the way they all work. The system I had in my house in Watertown (whose manufacturer I don't recall) heated the water -independently- of heating the water that heated the house and/or running the pumps, but all in the same furnace. It did a fine job. Infinite hot water. And apparently efficient---in the summer months, I noted a trivial (5%?) decline in my oil tank across 2-3 months. In other words, the bulk of the oil was going to heat the house, not the domestic hot water, and the oil gauge basically didn't move -at all- in the months that the house wasn't being heated---I can't discount the possibility of the slight use I did see being used to heat the house on the occasional chilly night. --Lenny > That is -certainly- not the way they all work. In fact, that's how none of them work. As I remember, and from all the evidence I've seen, you -never- run well (or city, or whatever) directly through a boiler into your hot water system, where that water will end up in a shower or as drinking water. Why? Just open the stopcock on the water that heats your house someday (it's a closed loop). The water is -black-, due to things leaching off the inside of pipes that are exposed to the heating flame. 'potable' hot water in a residence is handled in one of two ways. Either there is some sort of heat transfer mechanism, where (and sometimes i get these backwards) either the potable water is inside the coil, or in the small tank - i think the potable water is in the tank), and a coil runs the house heating water through it to heat the water. The house heating water and the drinking water -never- mix. The other source is a traditional hotwater tank, which has its own heating element, etc etc. I'm suspecting what wex is seeing is one of these 'coil' systems, where the furnace heats the house circulating water, that water circulates through the holding tank coils which heats up the water in there, and after a bit, you have hot water. :) These coil systems are very common in low-cost installations, since they're dirt cheap, and work okay. However, if you don't have your heating system tuned right, it can be a major hassle. There's a thing called a tempering valve which adjusts how much water coming out of this hot water reservoir is mixed with normal well/city water. That determines how hot your potable water can get. There are also valves which _should_ turn on and off circulating water to other heat zones in your house. If these valves aren't working right, you can end up with the situation wex is describinb, where you have to heat up the entire system just to get up to temperature in the coil heater. Much of this is coming from my experiences in our house in Natick, which had one of these coiled transfer tanks, which sucked, cuz it didn't have much capacity, and the zones in the house were not working, so it took forever to get hot water back up. You might want to have a plumber trace your pipes and see if you have a lot of dead pipespace, bad valves, or a busted tempering valve. --Dave Belfer-Shevett I think this must be age-dependent. I have the old-fashioned tankless system mentioned above, and it does indeed work as stated (have seen the thing partly disassembled; a coil in the boiling tank for our (steam) heating system; also, activation mechanism for better hot water is to turn the house heat up...). And they do suck. Have also seen a more modern version that feeds a little 5 gallon tank; I guess this gets you past the transient where the furnace is still cold and you are asking for hot water. Person with that system said it was OK, but he was the cheap sort that probably took < 5gal showers anyway. -h The system I had was in a furnace about the size of a medium-sized cube fridge, and was newly-installed around 1986. There was no tank in evidence; certainly a five-gallon tank would have been obvious. The only tanklike thing anywhere was the thermal-expansion tank in the heating pipes---not in domestic HW. It supplied hot water "instantly" and with no noticeable temperature fluctuations for as long as you cared to run it---certainly 20-30 minutes. If it had been a long time since the furnace had been PM'ed, it tended to run a bit cool, but cleaning the furnace and replacing the ignitor at regular intervals (both standard for an oil furnace) fixed that. --Lenny I think I have this same system. Heats the water independantly of the house; there's two valves and two entirely separate water systems. Don't know if i like it or not; haven't lived here over a summer yet. --karyn There are four basic types of hot water heaters. The conventional hot water heater is a big tank (40 gallons or so) that has its own heat source (gas or electric). Then there is the system where you have a large tank that gets its from the furnance and it operates as a separate heating zone (this is the system I have, I use one tank of oil for the entire summer). Then there is the tankless system which is heated directly by the furnace. Guessing by the brand name, the system Mark is talking about it's a completely different system that's much more common in Europe. Instead of having a big tank, you have a little device that instantly heats the water as you need it. I don't know how efficent they are, but they seem pretty popular, and in Europe Bosch makes lots of home appliances (washing machines, dishwashers, fridges, ...). --Ben Theresa and I have tankless hot water on our four-year-old Weil-McLain model 68 (with Beckett AFG burner, should anyone find it relevant). I believe it does maintain the in-core loop at high temperature at all times, though this is not at all the same as heating the whole house, as the house circulation pump does not run except when the house needs heating, and in any case, summer oil usage is imperceptible. We had noticeable problems with temperature regularity until our new, competent furnace guy changed the range and hysteresis to non-intuitive but very effective settings; since then I've been absolutely delighted with the system and would not think badly of replacing it in kind. --andrew Thanks for all the suggestions and advice. I've decided to go with the Bosch AquaStar 125B. It will be installed on monday. I'll report back with my experience once I have some. Maybe I'll even put together a sermon for the web page. --Marc |
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