How to maintain boiler (oil) after removing coil and adding electric water heater?

TrDs · January 15

Need advice. Plumber said my coil is insulated (because water hot then cools off rapidly, then hot again, repeat). Recommending removing coil and adding an electric water heater. I like the efficiency of instant heat system but not sure I want to deal with potential installation issues and future maintenance. (Electric water heater simpler though I know I'll need to replace and not as efficient. Should I consider other options??). How do I maintain the boiler May to November when it won't be needed for hot water? I understand that shut off is a bad idea. (Solar panels will help with electric cost. System is a Peerless Series WBV, 8 years old, water is from a well, house has a water softener and house filter. I was surprised the coil went.) Long time home owner here and special ed teacher in regular life. But, don't assume I know anything! I've just figured stuff out as it came along, took decent advice, and the place is still standing! Thanks.

Jamie Hall · January 15

All I suggest is maybe raising the water level a bit and… let it be.

Is the water softener the ion exchange resin type? If so do NOT use that water for the boiler — and it may be one reason why the coil went…

ethicalpaul · January 15

I understand that shut off is a bad idea.

I don't have that understanding

PS: I agree completely with your plumber, it is so nice to have those systems separate. If you really want to reduce the operating cost, consider a heat pump water heater and look for state and/or utility incentives

TrDs · January 15

Thanks, Jamie. I'll look into how the softener works. (All I know is I fill a plastic "tank" with salt and it fills with water from another tank and then magic happens and it all gets sent into the house. Not sure how to change that if it's a problem. The plumber who installed it knew my system. The last boiler coil lasted way more than the 8 I've gotten from this coil, and it didn't have a softener. So, that might be the problem, as you said. )

Ethicalpaul: I had heard/read that I don't want the boiler to get too cool because that contraction and then expansion again is not great for it. But again, I just need to trust what experienced people tell me. I WILL look into a heat pump water heater. Hadn't thought of that. Thanks!

If the boiler is just doing heat, it seems to me it won't turn on from May to Nov (when I don't use heat). Just wondering if that will create a problem I need to head off.

EBEBRATT-Ed · January 15

When the coil is removed or disconnected you disconnect the low limit control. Right now the boiler responds to the thermostat for heat and to the LL control to maintain a minimum boiler temp for domestic hot water. When you put a new WH in (standard electric water tank) you disconnect the low limit wires .

That way the boiler will only respond to the thermostat.

The boiler going cold in the summer is not an issue.

TrDs · January 15

So clear, Ebebratt-Ed. You must be a teacher! Thank you!!

LRCCBJ · January 15

https://forum.heatinghelp.com/discussion/comment/1835075#Comment_1835075

He's a professor.

HVACNUT · January 15

Is this steam or hot water?

Where are you located? Is electric cheaper than oil?

I'll assume not steam. At 8 years old, the WBV came with the Hydrostat 3250 Plus? How many zones? An indirect water heater might be the most efficient and cost effective. If the boiler has the Hydrostat, it can be still be converted to Cold Start. It doesn't sound like the plumber is a boiler guy.

An indirect would add a heating zone to heat a tank. Typical heat loss on an indirect is 2° an hour. So if everything is just sitting there doing nothing, the burner will come on every 5 hours for about 10 minutes.

I like that my boiler gets daily exercise and doesn't sit like a lump on a log for 5 months.

SuperTech · January 15

I'm also a big fan of having an indirect water heater. I've had an electric water heater and it was terrible. Limited hot water capacity, super slow recovery times from hot water usage, and the quality of the average electric water heater is horrible as well. They do make much better ones than the one I had. But I installed an indirect water heater and have been much happier. My electric bill went down significantly and my oil usage over the spring and summer is barely noticable. I've never run out of hot water no matter how much demand I put on the indirect tank. With the aquastat set to cold start the oil burner only fires a few times a day to maintain the temperature of the indirect tank. Depending on fuel and electric costs this might not be the best choice for you but I couldn't be happier with mine.

TrDs · January 15

HVACNUT: It's hot water, not steam. Oil is cheaper than electric but my solar panels offset my electricity costs in a big way. It has a Hydrostat. 2 zones. (One I only turn on when it's super cold. I use an electric heater instead or keep the room cool.) Plumber mentioned having to add a zone when I was considering an electric tankless water heater. I am concerned about not running the boiler for months. Downside to indirect water heater?

hot_rod · January 16

how much hot water do you need or want?

For most folks, two people in the household a 50 gallon electric water heater is fine and with PV it may not be expensive to operate.

If you had a large family or big bathtubs to fill, electric may not be the best option.

All cast iron boilers that do not have a coil or indirect sit all summer cold, without any issues.

An electric tank will be much less $$ to install, compared to an indirect.

EBEBRATT-Ed · January 16

@LRCCBJ

Thanks. 😊

But you never saw my report cards when I was in school. That's because I threw them down the storm drain on the way home.

Definitely not a professor.

EdTheHeaterMan · January 16

@TrDs said: "I understand that shut off is a bad idea."

I just read the entire I/O manual for the Peerless Series WBV and see no mention of this shutting off being a bad idea. Depending on the Aquastat Relay that you have on that boiler, all you need to do is make some minor adjustments on it to make it a cold start boiler. I also agree that using a tankless coil for making DHW is not the best idea, but using electricity to make DHW might be a worse idea. It all depends on the price of a kWh of electricity versus the price of oil in your region.

The 8 year old boiler may have come with a L8124A Aquastat relay and that is the easiest one to change from the maintaining temperature for DHW to the Cold Start control. You just remove 2 wires and wire nut them together. If you have the L7224C control, sometimes the low limit can not be turned off, but you can reduce to the lowest setting of 120°F to get as close as possible to a cold start boiler without replacing the control If that is not the original control and you have the L7224U then you can turn off the low limit feature. Some of the newer WBV boilers have the HydroStat 3250. That one should also have a way to turn off the Low Limit. In any case you will be better off with a cold start boiler if you are not going to use it for making DHE with the tankless coil.

After you figure out if you want to do the normal maintenance that a tankless water heater requires, and continue to use oil for your DHW, then there are 2 choices in my opinion. The tankless is the less desirable way to make DHW with your oil heater. Using an indirect DHW tank and setting up your boiler to operate as a cold start will be a much more efficient use of your oil. Of course those tanks are more expensive to install, but you will find that they last much longer than a standard electric water heater tank. Sometimes 2 to 3 times longer. There are still manufacturers that offer Limited Lifetime Warranties on indirect water heaters

Peerless even has the piping and wiring schematic in their I/O instruction manual. I can explain why I believe that an indirect DHW connected to a high efficiency boiler is better than a tankless coil if you really need me to. But I think your best option now is to see if electricity is a cheaper energy source compared to oil, and when you find that oil is less expensive, you can get the proper maintenance for your tankless and keep things as they already are.

I had one thought about your problem with hot cold hot showers… Do you have more than one thermostat in your home? If you do, then your water heater is not the problem. It may be the way that the second thermostat is connected to your boiler. I would like to know if you have more than one zone.

TrDs · 2:39AM

EdTheHeaterMan: Thanks for all that info. I do have 2 thermostats. The one in the bedroom does supply heat to the (one) bathroom. The other zone is living room/kitchen/one bedroom. My boiler has a Hydrostat. What might the issue be other than an insulated coil? The plumber made that assessment based on my description of the water initially being very hot and then cooling off and then heating up again. (Also, I have been told that the cooling down of the boiler and then the heating up of it again wasn't good for it. Contraction…expansion…unhappy boiler.)

EdTheHeaterMan · 3:55AM

The other thermostat, the one that is not connected to the Hydrostat, what control is it connected to? Is there a circulator pump for the other zone or do you use two zone valves?

If you are using 2 circulator pumps, are there any wires connected to the ZC and the ZR terminals on the HydroStat?

ZC and ZR on the HydroStat are there if you use 2 zone circulator pumps. If you do not use them, then you have one circulator pump that is not turning on the burner and it is pumping cold radiator water into the boiler when the circulator should not run at all. If that happens when you are taking a shower, then the boiler water temperature may drop too low to maintain DHW temperature at 120°F Then you get hot/cold/hot water when that happens just like you explained.

EdTheHeaterMan · 5:06AM

With the off chance that your other thermostat (we will call zone 2) is operating a circulator zone and the person that installed zone 2 did not connect the ZC and ZR wires to the zone 2 control, this is what you need to do.

If you do not already have a R845A switching relay or a Taco SR501 switching relay or something equal, you will need to purchase one of those relays.
Connect the ZC wire to the #1 terminal on the R854A as shown in the attached diagram. this will only allow the zone 2 circulator to operate if the boiler water temperature is high enough to maintain a minimum 120°F DHW temperature. If the boiler temperature is too low the zone 2 circulator will not operate.
Connect the #6 terminal to ZR, in order to operate the burner when zone 2 calls for heat. This way the burner will not be playing catch up as it is currently.
Follow the diagram for all the other wires (shown in blue) needed to connect the zone 2 thermostat, pump and power wires.

Maybe your water heater is not broken or clogged up with calcium. It was just wired wrong.

HVACNUT · 11:36AM

https://forum.heatinghelp.com/discussion/comment/1835091#Comment_1835091

Definitely go with an indirect. But it must be wired as shown in the Hydrostat manual so the Economy mode is bypassed when there's a demand for DHW.

psb75 · 12:01PM

Definitely go for an electric heat-pump water heater because 1.) of possible incentives and 2.) you have solar pv input and 3.) there is no downside to having yoour boiler NOT RUN in the warm months of the year.

How to maintain boiler (oil) after removing coil and adding electric water heater?

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