Should I stop water heater maintenance?

[Robert Snow]

My GE 40gal water heater is 23 years old. I replaced the anode rod with a magnesium one at the 10 year mark. The original was almost completely gone. After 5 years I took it out and it looked pretty gnarly. It could have gone another few years, but I replaced it with a new one. Now, another 8 years has passed. I replaced the thermocouple once and when the gas company ran new lines in the street last year they changed it again because they could not get it to stay lit. We have city water and there is never much sediment when I do drain the tank using the plastic valve that came with the heater. The basement is unfinished and there is a sump pit and pump nearby. I never did maintenance on our previous two water heaters. They didn't last nearly as long and each failed suddenly, with significant leakage but did no damage. I was able to replace each of them within a day. I plan to shut off the water to the house whenever we are away on vacation. If experience holds, the rod should be gone in a couple of years and the tank would lose its protection. If I change the rod on such an old tank, it might be too fragile and spell the end. Should I leave sleeping dogs lie or change the rod at a time that would be convenient to replace the heater just in case things don't go well?

 

[WorthFlorida]

The same energy bill that outlawed incandescent light bulbs also changed water heater efficiency and it created big improvements to meet the new energy requirements. For gas there is a slew of different types that may take some research. Lately, the electric heat pump water heaters seems to have good reviews. Originally the complaints was noise and slow recovery but all water heater exterior dimensions changed by an inch or two.

I would replace the water heater for one, lower operating cost and two, piece of mind not having to worry about a blow out. You don’t want it happen on Christmas Eve or the day before a wedding. FYI, all new water heaters require and expansion tank from the manufacturer's and local codes are also requiring an expansion tank.

https://smarterhouse.org/water-heating/replacing-your-water-heater

 

[Sponsor]

 

[Sylvan]

Replace the tank Yes

Why does a code require and expansion tank?

When water is heated it does expand BUT before a tank is required the incoming pressure should be known before wasting money on add on that may not be needed

NYC has water pressures from 6 PSI to over 85 PSI and I yet to install a expansion tank on a water heater. I have installed a PRV to bring the pressure to about 60 PSI or less

On a hot water heating boiler yes as the relief valve is set for only 30 PSI in most cases

 

[WorthFlorida]

As you know locals code vary so when a plumber comes out to install and states that an expansion tank is needed, not to be surprised.

Many old homes have had the water meters replaced and all new meters have built in check valves, therefore, the home becomes a closed loop including installing a PRV. In Florida ground water temp is 75 degrees, in Vermont about 38 degrees. Heating very low temp will create a lot of pressure and the T&P only opens at 150psi, that is a lot of stress on the plumbing before it opens. When someone tells you I heard a bang when the water heater blew, it was the pressure breaking a weak part of the water heater or a washing machine hose burst.

See page 22, warranty is not covered without an expansion tank.
https://www.hotwater.com/Resources/...®-XE-Power-Vent-40/50-Gal-Manual-(100271615)/

 

[Robert Snow]

Looking at overall energy use, the water heater is a drop in the bucket. Our house was built in 1927 and heating/cooling dwarfs all other energy use. There are five bedrooms with a 12' ceiling in the master bedroom. Only two of us now and looking to downsize in five years or less, when we leave the region. Converting the values from the old energy star guide on the GE (made by Rheem) and comparing to a same size new Rheem, the savings would be $18 per year (corrected) maybe less with only two of us. Our cast iron boiler is a much bigger issue and was manufactured in 1980. Working great, but inefficient. If I replace it before we move, I'd consider an indirect tank for water heating.

When you own an old house, you take the long view towards the physical plant. We replaced the single glazed steel casement windows with sealed double glazed units. We replaced the ancient central air system from the 1970's with a far more efficient unit. Added attic insulation, but no easy way to insulate the plaster on brick walls. Also replaced a 1976 gas pool heater with a heat pump.

 

[DIYorBust]

For my 2 cents I'd try to change the rod, if it can't be done it's time for a new heater. If you're short on cash, you could wait until replacement is feasible to try changing the rod. I don't see an advantage to just letting nature run it's course as it could easily happen at an inconvenient moment.

 

[Dana]

Looking at overall energy use, the water heater is a drop in the bucket. Our house was built in 1927 and heating/cooling dwarfs all other energy use. There are five bedrooms with a 12' ceiling in the master bedroom. Only two of us now and looking to downsize in five years or less, when we leave the region. Converting the values from the old energy star guide on the GE and comparing to a comparable Rheem, the savings would be $40 per year or less considering our reduced need for hot water. Our cast iron boiler is a much bigger issue and was manufactured in 1980. Working great, but inefficient. If I replace it before we move, I'd consider an indirect tank for water heating.

A 40+ year old gas fired cast iron boiler isn't likely to be hitting it's ~80% steady state thermal efficiency, and could easily be in the low-70s for raw combustion efficiency. At 3x oversizing for the heat load at the 99th percentile temperature bin it's as-used AFUE is going to be 10% or more lower than it's steady state efficiency. Between the standby, distribution and cycling losses, replacing it with a right-sized modulating condensing boiler could easily knock off a third to half the heating bill.

If you were re-designing the radiation &/or re-zoning a full-on Manual-J would be useful for sizing the radiation & boiler. But for a just a boiler swap, a fuel-use based load calculation (which is a measurement, however crude) is just fine, often better. Using the nameplate efficiency of the old boiler as the calibrated measurement interest will automatically build-in an oversizing factor, but not an insane oversize factor. If a burner tech has tested the raw combustion efficiency in the past 5 years you could use that rather than the nameplate efficiency, but in most cases that won't change the boiler sizing.

Bigger is definitely NOT better when it comes to heating & cooling equipment. The house is more comfortable during the outdoor temperature extremes if it's running very long duty cycles. While ASHRAE recommends 1.4x oversizing to allow for deep overnight setbacks and cover temperatures colder than the 99% outside design temp, with a modulating condensing boiler even 1.2x is usually overkill. Some amount of analysis of the radiation & zoning needs to be done when moving from a higher thermal mass cast iron beast to a low-mass mod-con, but it's not rocket science. The napkin math is good enough for sizing the minimum-fire output of the boiler.

There are some pretty good yet relatively inexpensive stainless fire tube modulating condensing boilers out there these days (eg distributor pricing on an 80K or 120KBTU/hr HTP UFT series is under $2K). If the heating cost is far and away the primary energy cost for the house getting rid of the beast in the basement sooner than later may still pencil out in short years, and could improve resale value.

In a damp basement doing the hot water with a heat pump water heater takes a big chunk of load off the dehumidifier, converting the latent heat of vaporization of the water it's taking out of the air into sensible heat inside the tank. Even if the water heating cost is comparable to that of a mod-con + indirect when viewed in isolation, if you normally need a dehumidifier to keep the "musty basement" smell at bay a heat pump water heater has a lot going for it.

 

[Robert Snow]

I'm thinking that changing the rod with a plan to replace the heater the same day, in case something goes wrong, makes the most sense for me. Not short on cash, but as important as it is to conserve energy, putting a working appliance in a landfill while it is fully functional has some environmental cost.

I was not aware of the expansion tank issue and can see why it is needed in a closed system. The gas and water lines in my street were replaced last year. I would assume that if the water company installed a new meter with an internal check valve in a house with no expansion tank, they would be incurring some liability. Here's a photo of the new meter. Nothing else was installed in line with it. Anyone familiar enough with these to know if this type has a check valve? Body seems kind of small for any kind of internal valve.

 

[Dana]

Integral check valves aren't very big, but you're right it's pretty diminutive. Is there a model number on that meter? Is that a Neptune T10?

 

[Robert Snow]

Great advice on the heating. Our heating bill went down significantly when we replaced the old steel windows. Ice actually formed on the inner mullions on cold winter days! Our electric bill went down significantly when we replaced the cooling system. Big savings too with the heat pump for the pool.

When we moved in, 28 years ago I added an Extrol tank, automatic fill valve, air vent and a Grundfos three speed circulator to the boiler. I also removed an old oil tank and saw evidence of a coal chute. Many different fuels have been used. Fortunately somebody installed iron baseboard radiators throughout the house and they provide quiet even heat. One zone unfortunately. Boiler is of course somewhat oversized due to all the changes we've made to windows and insulation. It was barely able to keep up when we moved in. And yes, all of the houses on the street have wet basements. Great idea about the heat pump water heater, because the dehumidifier does run quite a bit. One house on the block still has single pipe gravity steam heat and the new owner replaced the ancient boiler with a new steam boiler. All he could afford to do. House still had steel windows with single glazing and he replaced them with cheap looking double hung wood windows instead of casements.

 

[Robert Snow]

I was being lazy. Water meter is Neptune T-10 H65N. Checked their website and no mention of a check valve in the description. I have no idea what the water pressure is coming into the house, but it does not seem excessive. Easy enough to add an expansion tank if I install a new water heater if required by code or manufacturer's warranty. If I go with a heat pump water heater, the warranty is going to matter a lot more to me. It's been a lot of work to bring this house back.

]

 

[Dana]

Running it as a single zone isn't necessarily unfortunate, as long as the room to room temperature differences are pretty small, indicating a well thought out radiation sizing. It may or may not be easy to break it into zones by floor when the time comes, but don't micro-zone it without doing the math. The water volume/thermal mass of cast iron baseboard buys you something, but it's not the same thermal mass of full height rads of similar output.

Is that looks like 6 or 7 plate Weil McLain EG65 or EG75 trying to hide behind that water heater(?). With an automated flue damper it might have tested in 83% steady state range when new, probably 75-78% after 45 years. It may be oversized for the amount of radiation you have, but you can test that by adding up the square feet EDR of all of the baseboard (or the linear feet if it's all the same height). It takes about 450-500' of the 9.5-10" tall cast iron baseboard to deliver the full DOE output of the EG75, about 400' to emit the full DOE output of the E65. At an entering water temp of 180F figure on ~500 BTU/hr per running foot of the ~10" cast iron baseboard. It's pretty common to see cast iron boilers with twice the output of the radiation they're hooked up to, which doesn't heat the place any better than a boiler half the size.

But maybe I'm overestimating the size of the boiler from the camera angle. What does the nameplate have for input and output BTU (or MBH)?

 

[DIYorBust]

It's a great house. Where are you located?

 

[WorthFlorida]

Check with your gas company, there is usually rebates available for replacements to more efficient gas appliances and that may include boilers or furnaces. Can you transplant that apple or cherry tree to my house in Florida?

If the meter doesn't have a anti backflow or check valve, one is installed at the meter connection.

 

[WorthFlorida]

This was at my son's house in Altamonte Springs, FL. I went to turn the water off since I had to repair the water entrance to the house. It's Florida so everything is 6" below ground. As I turned the shut off valve, extremely hard, the meter moved a little and this connection started to leak. The weird looking device is the backflow preventer. Yes, most in Florida homes built in the last forty years uses PVC from the meter. This house was built in 1977, however, it looks like this line was replaced not long ago, the work at the house entrance need some improvement and had to add a spigot.

 

[Robert Snow]

Running it as a single zone isn't necessarily unfortunate, as long as the room to room temperature differences are pretty small, indicating a well thought out radiation sizing. It may or may not be easy to break it into zones by floor when the time comes, but don't micro-zone it without doing the math. The water volume/thermal mass of cast iron baseboard buys you something, but it's not the same thermal mass of full height rads of similar output.

Is that looks like 6 or 7 plate Weil McLain EG65 or EG75 trying to hide behind that water heater(?). With an automated flue damper it might have tested in 83% steady state range when new, probably 75-78% after 45 years. It may be oversized for the amount of radiation you have, but you can test that by adding up the square feet EDR of all of the baseboard (or the linear feet if it's all the same height). It takes about 450-500' of the 9.5-10" tall cast iron baseboard to deliver the full DOE output of the EG75, about 400' to emit the full DOE output of the E65. At an entering water temp of 180F figure on ~500 BTU/hr per running foot of the ~10" cast iron baseboard. It's pretty common to see cast iron boilers with twice the output of the radiation they're hooked up to, which doesn't heat the place any better than a boiler half the size.

But maybe I'm overestimating the size of the boiler from the camera angle. What does the nameplate have for input and output BTU (or MBH)?

Here's what I've got. Weil McLain CGM-7 with BTU/hr input 210,000, Capacity 165,000 BTU/hr. First floor has 80' of 10" high cast iron baseboard. Second floor has 115' of 10" high cast iron baseboard. The house is L shaped, which is great for natural light, but there is a a lot of surface area and rooms typically have windows on two or three sides. There is an unheated two car garage on the first floor with a bedroom/bathroom suite above, so less radiation on the first floor. There is no insulation between the radiators and the plaster on brick walls. Lots of windows. Largest is 72" x 54". When there was no attic insulation and single glazed steel windows, the furnace seemed good in all but the worst conditions and could not get the house much above 60º F when temperatures dipped into the single digits even with the limit control set just above 200ºF. We are in the Philadelphia suburbs. With insulation and replacement windows the available radiator capacity seems to be adequate with the furnace clearly oversized. The basement is unfinished, but there is a laundry and workbench down there. The temperature in the winter is also very comfortable from heat of the boiler and pipes running all along the ceiling, which I have insulated with foam wrap. The vertical runs of the loop are not insulated and are in chases that probably lose a good deal of heat to the outside and the attic. The limit control is now set to 190ºF and Grundfos 3 speed pump set to medium speed. The rooms are all at about the same temperature during the heating season and very even.

First floor is a bit warm in the summer, since all of the AC is distributed from the second floor ceiling. I added large grills at the top of each stair and it works well enough now. It is my understanding that the previous owner was an HVAC contractor and installed the heating and central air. He also had the pool and pool heater installed in the mid 1970's. Unfortunately he also installed 2x4 lay-in ceilings in the kitchen and three bathrooms all with fluorescent lights. Indoor outdoor carpet in the kitchen and wall to wall over all the pegged oak floors. Wet basement was also "finished" and smelly with mold behind the walls. I filled a couple of dumpsters right away and found the "wiring" in the basement consisted of extension cords spliced with wire nuts.

 

[Dana]

At an entering water temp (EWT) of 190F and an average water temp (AWT) of 180F, typical 10" cast iron baseboard is delivering about 590 BTU/hr per foot. So with 175' of baseboard the most the radiation can deliver is 590 x 175' =103,250 BTU/hr, whether it has a 105K-out boiler behind it or a 500K-out boiler behind it. So with 165K of boiler output an 103K of radiation output the boiler will always cycle on/off during an extended call for heat at about a 62% duty cycle. That's not great, but I've seen worse.

Somewhat newer CGM-7s delivered about 172K , for a 82% steady-state efficiency, whereas yours started out at 78.5%, and is probably closer to 70% now. (A CGM-5 of the same vintage would heat the place just as well as the CGM-7 does, but wouldn't cycle on/off if running it at 190F.) When running the fuel use load calculation assume 78.5% efficiency, and use +15F as the outside design temp. (That's Philly's 99% outside design temp.)

Most mod-con boilers max out at 180F, so you'd be looking at a max AWT of about 170F, and the radiation would deliver about 500BTU/hr per foot for ~87,500 BTU/hr, so no matter what there would be no point to installing anything bigger than a 100KBTU-in boiler (which will deliver about 88-89,000 BTU/hr at 180F output.) But if you run the fuel use load calculation you may find that your actual 99% load is quite a bit lower than that, and could be cut down to size with a few insulation improvements. Getting rid of the CGM and sealing up the flue probably reduces the infiltration load by a 2000 BTU/hr, and the reduced jacket losses to the basement is probably good for another 3-5000 BTU/hr.

Even if you're not planning to turn it into fully finished living space, one of the locations that's probably accessible for insulating without major demolition is the basement walls. Insulating the foundation walls with 2" of continuous sheet polyiso (R11-R13) will bring it up to current IRC code minimum (=R10 continuous insulation), and would likely knock a full 10KBTU/hr off the heat load. Even though the basement may not be actively heated, that WILL show up in the fuel use numbers, and will reduce the amount of heat that needs to be emitted by the first floor radiation and increase comfort- the floors will be a degree or three warmer, a subtle but real comfort upgrade. In the Philly area you can sometimes get used roofing foam for dirt cheap from Repurposed Materials Inc, but there are others often advertising here. If you think that's a project you'll take on check back here, there are a few things to get right to make it a long term trouble free solution.

 

[DIYorBust]

Dana, including the increase in real estate value, and the energy savings, which projects do you think would break even in 5 years?

 

[Robert Snow]

Real estate value is a tough one. These houses were part of a development back in the 1920's surrounding a golf course. After the war, the golf course was turned into a massive apartment complex. The typical house in the area is quite small by comparison. The last three houses that sold on the block were total wrecks and probably cost more in renovations than the selling price. Renovations were typically cut-rate. The big houses from that era that are generally well kept are nowhere near the level of repair and interior finish of our house. The selling price is going to be heavily constrained by all the past sales. Good news is that we are on a trolley line to Philadelphia and younger home owners are flooding in right now, to some extent lured by the low prices and proximity to the city.

 

[Robert Snow]

Quick question. With the current boiler oversized, would it make sense in terms of energy savings to lower the limit control to 180ºF? Would it be a good test to see if a new ModCon boiler with that as the max would be constrained by the amount of radiation in the house? Our chimney never had a cap until we added one. Our last cleaning and inspection went OK, but we were put on notice that we might eventually need a liner and that could push us to a ModCon.