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Water Heaters 101 > Water Heating
According to Larry

What This Is About

Larry and Suzanne Weingarten pioneered the concept of water heater service and invented tools and techniques to make that possible.

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Larry is a frequent contributor to The Tank, our forum. He told me recently that he was using his answers there to fill in gaps in knowledge so that a person could, by gathering various questions and answers, learn his philosophy about water heating.

The Tank has become truly deep -- there are so many posts that it's hard even for me to find any given one, so I decided to do the gathering myself. This page is the result.

Sometimes there will be multiple questions, partly answered by Larry, partly by one of the rest of us. The fairly regular contributors are Larry, Ej, Elenano (me), EnergyExpert and Undees.

-- Randy Schuyler, 1/26/10

Water Heater Vs. Boiler Vs. Tankless

Q: I'm responsible for a church facility with a modestly-sized preschool and a small kitchen (licensed commercial). I have funding to junk the ancient boiler supplying the facility (hooray). But I have to support peak use of the dishwasher which needs 50 gal per hour of 140 degree water (it has its own booster to take it to 180). This gets used infrequently but for health department it has to work when needed. The only other use for hot water is some hand sinks in bathrooms.

So my choices are: 1) commercial tank -- at 140 degrees using a lot of kW (or BTU); while small (50 gal) it will be running 24/7; 2) tankless -- large expensive unit to supply the kitchen (and/or small point of service to supply hand sinks); 3) combo -- wimpy-ish tank unit running 24/7 and then a booster in the kitchen to supply 140 degrees -- the hand sinks supplied by the wimpy unit Wow is this a fun question or what? Not so fun for me though. I have the best plumber and best electrician ever, ready to support whichever choice we make. What do you think?

Larry: One way to deal with this would be to plumb two tanks in series but creatively. Run cold into one tank set at 120 degrees. From this tank feed the sinks and feed the second heater. Set the second heater at 140 and turn it on when you plan on using the dishwasher. This gives you a two temperature system so you get sanitized dishes but not scalded hands. Modestly sized heaters would work as they would share the load.

Water Heater Vs. Boiler

Q: My condo building is shopping for a new water heater. We currently have a 100 gallon A.O. Smith that has a gas burner underneath it. A couple of the proposals we've received have a separate heater that stands along side a storage tank. This type of system is a bit more expensive than one like we currently have. For example, an A.O. Smith Commercial Water Heater, HW-200 with a Glass-lined commercial storage tank TJV-120. Another company proposed a Teledyne Laars PW250 with a storage tank. Can anyone please give me some advantages for a system such as this?

Larry: In general, a separate tank and heater (boiler) have the advantages of less standby heat loss from the tank and the possibility of more efficient heat transfer in the boiler. Also, either unit can be replaced separately. The downsides are greater cost and more complexity. I'd try to understand the lifecycle cost of either way of going. So, add up the initial cost, the yearly energy savings and the yearly maintenance. At some number of years down the road, you'll have a clear winner. The winner needs to be cost effective before it wears out. As an example: if a standard tank costs $1000 and a separate boiler/tank costs $2000, there is $1000 to make up. If the boiler saves $200/year, it pays for the difference in five years and saves money from there on out. However if there is $100 of maintenance yearly, that break even point is now ten years out and the question becomes "Is the equipment going to last ten years of more?" The figuring can be made more complex by trying to add in the time value of money, buy I'm only a plumber.

What Fried This Electric Heater?

Q: Our water heater stopped working so I went to check it out and it had black fire marks on it under a panel, so I opened it up and this is what it looks like. I made a small minute video of it. tell me what you think. http://www.youtube.com/watch?v=8qyclu3ZfCU

Larry: New thermostat and new wiring could fix it. Make sure the plastic cover and insulation go back over the new stuff. I'd be very certain there is no moisture around, as it could be the cause of the trouble. One other thing, were there any voltage spikes (storms, power outages)? That can cause trouble as well.

Squeaking Around Having the Wrong-Size Vent

I just replaced my 50 gal heater with a new 75-gallon unit that I modified with the Water Heater Rescuer kit (second anode, curved flush tube, better drain). Everything went fine on the install and it is working great but one thing that concerns me is the venting. My house is not that old(10 years) and has a 3" vent going straight up from the water heater closet, through the second story to the roof(full compliance) The vent on the 75 gallon heater is 4". Am I okay with using a vent reducer from 4" to 3" right above the vent hood. I have the water heater set to 140 degrees max. I have approx 18" clearance from the top of the water heater to the ceiling where the vent goes into the drywall(specs require 12" minimum) I know that the vent tubing gets scorching hot even up to where it meets the drywall. I want to make sure it is compliant, but since my house is plumbed for 3" I am not sure what options I have other than to reducing it. Is it okay to reduce it? Or would I be better off using a 3" vent hood, so excess heat can vent out the sides of the hood? Any advice would be appreciated.

Larry: Normally a three-inch vent works for up to 40,000 btu. It might work for you to reduce the gas input to your heater so the vent can function correctly. That would mean it would take slightly longer to reheat a tank, but that normally is not a problem. Another thought is to actually check for spillage from the draft hood. If it does not spill combustion products into the indoor air, there is not a problem. Understand, code and the manufacturers and good plumbers would all say you must stick with 4" pipe. I don't know where that leaves me? Safety must always be the first consideration in any hot water undertaking. If it cannot be done safely or if it creates a potential hazard, don't do it.

Different Labs, Different Ratings

Q: I need a hot water heater that is gas, direct vent, .63 EF, and does not need electricity. Are there any on the market?

Larry: Here is info from AO Smith's site. Their heater is .62. Note that EF is not a particularly good or reliable or repeatable measure. The same heater can get different ratings from different labs. One point is basically unimportant unless there is some rebate or credit you're looking for.

Properly Pump Up Expansion Tanks

Q: I just installed my 4th water heater for the week and am rather tired of dealing with this problem. Somebody please help. The problem is that during the night the pressure relief valve releases water into my finished basement. I have installed a water expansion tank and am still having the same problem and a big mess in my basement. Any advice? My water pressure is 75 lbs.

Larry: A question. Expansion tanks come pre-charged to 40 psi. That's the most the Dept of Transportation allows. If you have 75 psi water pressure, the tank needs to be pumped up to 75 psi when it's not exposed to system pressure. Otherwise most of it's capability is lost. So, the question; did you pump it up? Beyond that a gauge would be nice to have on the system so you might catch any pressure spikes. One more question. Is there any pressure reducer, check valve or back-flow preventer in the system?

Building a Better Dielectric Nipple

Q: I have one more question concerning the combo magnesium anode. It is plastic-lined, but the plastic does not extend beyond the lip like it does on the existing dielectric nipple that came with the unit. Will it still function like a dielectric nipple, or do I have do something different to make sure I don't get corrosion?

Larry: There are small things those of us who work in the field would like to see manufacturers do. After years of nagging, some manufacturers actually put decent drain valves on their better tanks. Regarding the lined nipples, I'd like to see combo anodes where the lining went up and over the end of the nipple, but haven't. As standard lined nipples are available that way, it seems possible. Another approach would be to make plastic lined brass nipples. That way a little exposed brass up at the piping end wouldn't matter and if there were a little exposed down by the steel tank, it would have very little effect as the area of brass to steel would be so small.

Don't Just Replace; Rethink

Q:My 30-something-year-old oil-fired hot water heater is beginning to have some serious issues. Surprisingly, the tech that services it recommended going with an electric, I sort of was thinking that way as well after he quoted a price for a new one with installation, so I've started researching different brands at the local big box stores.

GE from Home Depot -- Made by Rheem appears to be a plus. Can't seem to find reviews on the GEs, which maybe indicates fewer problems(?)

Whirlpool from Lowes -- The "Energy Smart Control" looks interesting for possibly saving some money on usage, but some reviews from several years back indicate it had some problems with board failures. Have these controls been improved for reliability in recent years? Other problems indicated from reviews seem to be leaking of water at the tank top well be before warranty period is up. Has Whirlpool quality improved from a few years ago? One reason I was considering the nearby Lowes or Home Depot was the ready availability of basic replacement parts - heating elements. Kenmore from Sears - Believe it manufactured by the same company that does Whirlpool(?) Possibly similiar quality as the Whirlpool? From a few older posts I've read on this forum, GE seemed to be recommended over Whirlpool water heaters. Is this still the case? What's out there that might be a step above GE at a close price point?

Larry: I'll try to help, but can't answer some of your questions directly as I make little attempt to keep current on prices. What much of this site is about (in my mind) is sidestepping the merry-go-round of "replace heater with same, do nothing for ten years, repeat." That word repeat, it's a great way to double shampoo sales.

This site is also about how to make the hot water system perform better, saving water, energy and waiting time -- and doing it in a way that actually saves money over the long run. One usually starts with being in a great hurry as their tank is leaking. There are ways usually to remove that time pressure. It is possible to limp along with a failed heater if the leak is slow and if you turn off power and water when not using hot water. A hot tap needs to be left open also to prevent pressure build-up in the tank. That trick could buy you some time. I've had folks use it for up to three months. With time, now you can consider how to make the system do more for less as well as being able to comparison shop, get competitive bids etc.

Electric water heaters are really pretty simple animals. However, if they get at all wet on the wrong side, things turn nasty. So whatever heater you get, check the plumbing hookups again in six months to be sure they are still tight. Look into the element hatch covers to be sure you see no signs of water or arcing. With any of these, get the highest energy factor (EF) rating you can find. Rheem/GE is coming out with a new heat pump heater now which should cut in half the electrical energy usage. The industry has had a hard time making a reliable unit though, so make sure that if you get it, it has a strong warranty. The efficiency stuff mentioned in the earlier post earlier can easily cut your need for hot water in half, so go there first as efficiency measures are far more durable then complex equipment. Hope that helps!


Rounding Up Stray Current

Q: I thought I would post the following from a post I wrote in another forum ... my water softener guy was insisting that my water heater failure / anode rod consumption had something to do with electrical grounding. Don't have all the answers but he did call this correctly in terms of me having an issue I could point to. Thanks for making me think about this (in general).

Getting back to the electrical I analyzed my personal situation further. Traced out the point where the copper pipe connects to electrical ground wire at a saddle type connection right behind the cold water shut off valve. It appeared kind of ugly so got ready to probe with my multi-meter ... the damn thing was just sitting there loose! Thinking back I know when it happened. We've been in our home about 10 years now. During the first year the hot water heater was covered under one of these home warranties paid by the seller. So they came out, proceeded to wiggle the drain valve and flooded my garage. They then removed the existing water heater and came back the next day to finish the install. I remember these 2 guys were having major problems trying to solder a new cold water valve into place. I faintly remember them loosening that grounding clamp to help with the soldering.

Apparently 3 water heaters later (plus an inspection I had to pay the city to do) nobody caught the original screw up. Anyhow, I tightened it up, lightly filed at the wire and copper pipe so I could check for 0 ohms and hopefully things are better. Thank you Gary. Also wondering if my leaky pipe in the wall right next to the water heater was due to this issue. I also bought a powered anode rod from you guys. Hopefully my hot water related issues become a thing of the past!

Larry: There is likely a little more to it and understand I'm more plumber than electrician. Power coming into the house should consist of two hots and a third, neutral line. Usually the metal cold water line and gas lines are bonded and joined to the ground bar in the main panel which is also hooked up to the neutral bar.

Q1: My plumber's understanding is that ground and neutral are basically the same thing with different purposes. One is meant to conduct power while the other is a safety. In any event, you likely have a good connection to the neutral at the main panel, but the path to it is worth checking. I would also jumper between hot and cold with a #6 solid copper wire over the heater. Lastly, there should be a ground rod near the main panel and a #6 wire should be going from the ground bar in the panel to the ground rod. In recent bad old days, piping was used as the ground.

Larry: Done right, these things will get rid of stray current corrosion, which is when current has the option of going through the heater rather than directly to ground. If you do measure stray current, best track it down and fix it. Do talk to an electrician about all this and should anybody be able to clarify all this electricity for the plumbers amongst us, it would be appreciated.

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