Boiler Coil Water

[firebroad]

I just got an electric water heater installed, the first step in my replacement of the oil-fired boiler with a heat pump. I don't see a dedicated switch to turn off the coil, so I turned the Hi all the way down to 140, the Lo to 120, and set the diff up to 25.
Just wanted to know if this is the correct way to keep oil consumption to a minimum.

 

[woodgeek]

If you can turn it off completely (without it leaking) you should just turn it off until the fall. When I adjusted down the temps on my old boiler, it started sooting up a lot more. If I couldn't turn it off, your #'s seem ok and will reduce standby. Always have a CO detector with an oil boiler.

It might be a good idea to estimate summer standby, in minutes of runtime per day. I could hear my system kick on, and just noted the time between firings, and the duration, and figured out how many minutes it ran per day. IMO, 30 mins a day is pretty good for an old boiler on standby. When I started, I was running ~80 mins per day (!), because I had a 'thermosiphon' (slow circulation by natural convection). Closed a zone valve and it dropped to 30.

 

[firebroad]

Thanks WG, I was concerned about shutting it down, as I was under the impression it was not simple to turn it back on again. When I was a kid, I accidentally turned off our oil furnace, and my mother had to call the oil tech to get it on again; but then that might have been because she did not know what was wrong with it?

 

[TheMightyMoe]

It may leak if it is a older boiler with gaskets in the body. You should be able to turn it back on, and when it heats the gaskets will expand, and you will just leave it on all the time.

You can set your high to 180, as it shouldn't come on unless your home is calling for heat, in which case you'll want 180.

As for your low 120 will probably be fine. Some aquastats the differential only affects the HI, and the LO is a set #.

 

[firebroad]

It may leak if it is a older boiler with gaskets in the body. You should be able to turn it back on, and when it heats the gaskets will expand, and you will just leave it on all the time.

You can set your high to 180, as it shouldn't come on unless your home is calling for heat, in which case you'll want 180.

As for your low 120 will probably be fine. Some aquastats the differential only affects the HI, and the LO is a set #.

Thanks!
Now I have to get used to that water heater, I have to set it rather high to achieve what I got out of the boiler. Going to insulate the pipes this weekend.

 

[maple1]

You don't have to set your electric tank as high as the boiler was.

If I'm understanding right, you had a DHW coil inside an oil boiler? So that heats by passing the cold water through hot (boiler) water - therefore the boiler needs to be a lot hotter than the needed final water temp as it has to heat the DHW being used from a cold input temp (60°?) up to useable (110-120°?) in the short time it takes for that water to travel thru that small coil. There is no DHW reserve. In addition, the boiler water has to circulate to 'wash' the coil pipes with hot water, or else the coil will just cool off the boiler water immediately surrounding it and it will stop heating the coil. Throw in standby losses when nothing is happening (like heat escaping up the chimney or radiating off of pipes), and it's the least efficient way to heat DHW in the non-heating season you can find.

I used to have a coil in an oil boiler - now have an 80 gallon electric tank and the oil boiler is gone. I had the boiler set to a low of 140° in the summer, now the electric tank is set to a constant 115°.

 

[firebroad]

You don't have to set your electric tank as high as the boiler was.

If I'm understanding right, you had a DHW coil inside an oil boiler? So that heats by passing the cold water through hot (boiler) water - therefore the boiler needs to be a lot hotter than the needed final water temp as it has to heat the DHW being used from a cold input temp (60°?) up to useable (110-120°?) in the short time it takes for that water to travel thru that small coil. There is no DHW reserve. In addition, the boiler water has to circulate to 'wash' the coil pipes with hot water, or else the coil will just cool off the boiler water immediately surrounding it and it will stop heating the coil. Throw in standby losses when nothing is happening (like heat escaping up the chimney or radiating off of pipes), and it's the least efficient way to heat DHW in the non-heating season you can find.

I used to have a coil in an oil boiler - now have an 80 gallon electric tank and the oil boiler is gone. I had the boiler set to a low of 140° in the summer, now the electric tank is set to a constant 115°.

Yeah, it is a learning curve! I am not so happy with the water not being steaming hot, but I can get used to it. Also, the water heater is located under the bathroom, so there is instant hot water there. Unfortunately, that also locates it further from the kitchen, so I have to run water a long time before I get really hot water in the sink. No big deal, I can boil on the kettle if I need it hot right away. That's why I'm going to insulate the supply pipes.

 

[fbelec]

best way to get rid of running the oil in the summer is just to buy and install a reg aquastat and get rid of that triple aquastat. they are not to expensive. those dial are also for your heat so be careful not to forget when it comes to heat. sometimes the well where the probe goes in for the aquastat can get buildup around it and make the boiler have a delay when it needs to turn on and delay when it should shut off making the water hotter than needed. so when you buy a new aquastat get a strap on type and put in as close to the boiler on the supply side as you can then put a little insulation around it and your good to go.

 

[firebroad]

best way to get rid of running the oil in the summer is just to buy and install a reg aquastat and get rid of that triple aquastat. they are not to expensive. those dial are also for your heat so be careful not to forget when it comes to heat. sometimes the well where the probe goes in for the aquastat can get buildup around it and make the boiler have a delay when it needs to turn on and delay when it should shut off making the water hotter than needed. so when you buy a new aquastat get a strap on type and put in as close to the boiler on the supply side as you can then put a little insulation around it and your good to go.

Since the boiler will only be in service until either this year or next, as I am planning on replacing it with a heat pump, I probably won't take your advice, but the info is good to know.
I am kind of hoping I can afford the heat pump this year. I never thought I would live to see the day when electricity would be cheaper to heat with than oil, and I don't anticipate oil getting any cheaper like in the past.

 

[woodgeek]

I suspect that the event you recall when you were a kid was prob when your mom ran out of oil. The system has to be re-primed to get oil to the pump. In your case, you can just flip the switch to off, and back to on later. While there is a chance it might leak (a little) when it goes cold, there is a better chance it will not. Also, if it doesn't leak right away, it is prob not going to later. In the summer, the previous owner of my house turned the boiler off **daily** after his shower to save oil, for many years.

In the end, if you have new HW tank, and you can turn off the boiler, that is the way to save $$. We are talking ~$2/day during the summer, or ~$300+/year in oil. Also, IMO running these boilers at lower temps can also cause problems in the long run (caused by condensation of flue gases), they were designed to be run hot. Just pick a day you will be home, and flip the switch in the AM, and check on it every now and then as it cools off over several hours, and look for a puddle underneath. Once its stone cold, you can also turn off the cold water supply to the boiler (which makes up any circulating water that leaks/evaporates in normal use). This would also limit the pressure/volume/rate of water that did leak out later in the rare case it decided to leak later.

And then in a month or more when you want heat, turn the water back on, restore your original (hot) aquastat settings, and flip the switch to on. 5 minutes later it will be hot and ready to go.

 

[woodgeek]

If you are still nervous about 'leaks' Moe explained it well. The boiler is made of cast iron pieces hammered/clamped together and filled with 10-20 gallons of water. The joints are prob just iron squished up to iron, not one piece or soldered or welded or anything. But it works. Sometimes when a boiler cools off, the slight thermal shrinkage can cause those joints to open up a microscopic amount and drip. Usually, it doesn't. If it did, you can reheat the boiler, the joint will close back up and you'd be right back where you started, and any little water in the boiler insulation will quickly evaporate.

 

[maple1]

After my experience with Boiler Stop Leak stuff, I would not hesitate to shut down an oil boiler. Even if it did start a small leak, that stuff works.

 

[velvetfoot]

Are you going mini-split heat pumps? (I've been thinking about it too.) Even though you're in Maryland would you have to have some kind of backup heat? I don't know if the mini splits come with electric resistance.

 

[firebroad]

Are you going mini-split heat pumps? (I've been thinking about it too.) Even though you're in Maryland would you have to have some kind of backup heat? I don't know if the mini splits come with electric resistance.

I wish I could, they are so much more efficient!
In another thread, I learned a lot about heat pumps, the one I would be getting has a backup heater panel that kicks in when it gets below freezing. Of course, the heat pump, like the oil boiler, is really a back up for my insert.

 

[velvetfoot]

So, you are installing ductwork?

 

[firebroad]

So, you are installing ductwork?

Using the ductwork that was installed in the attic for the air conditioning. My nephew in law is doing the work, he does this for a living, and needs the money. I am just waiting for him to give me a price to find out if I can afford it this year or if I have to wait a year or so.

 

[velvetfoot]

Sounds like a plan!

 

[firebroad]

Thanks, VF. Now, getting the hot water to the kitchen without running it for ten minutes is the next task. Also, I hope I didn't pull a boner on the boiler; I threw the switch off last night, and forgot to check to see if there are any leaks this morning.
Oh well, how much can it leak if it is going to? I heard than Burnham's don't usually leak, so we will see.

 

[firebroad]

I suspect that the event you recall when you were a kid was prob when your mom ran out of oil. The system has to be re-primed to get oil to the pump. In your case, you can just flip the switch to off, and back to on later. While there is a chance it might leak (a little) when it goes cold, there is a better chance it will not. Also, if it doesn't leak right away, it is prob not going to later. In the summer, the previous owner of my house turned the boiler off **daily** after his shower to save oil, for many years.

In the end, if you have new HW tank, and you can turn off the boiler, that is the way to save $$. We are talking ~$2/day during the summer, or ~$300+/year in oil. Also, IMO running these boilers at lower temps can also cause problems in the long run (caused by condensation of flue gases), they were designed to be run hot. Just pick a day you will be home, and flip the switch in the AM, and check on it every now and then as it cools off over several hours, and look for a puddle underneath. Once its stone cold, you can also turn off the cold water supply to the boiler (which makes up any circulating water that leaks/evaporates in normal use). This would also limit the pressure/volume/rate of water that did leak out later in the rare case it decided to leak later.

And then in a month or more when you want heat, turn the water back on, restore your original (hot) aquastat settings, and flip the switch to on. 5 minutes later it will be hot and ready to go.

More than likely, because they were big old furnaces back then that had been converted from coal, it probably leaked all over the floor and she called the man in.

 

[velvetfoot]

I have a Burnham V8 type boiler and it doesn't leak operating as a cold start boiler.

 

[woodgeek]

Thanks, VF. Now, getting the hot water to the kitchen without running it for ten minutes is the next task. Also, I hope I didn't pull a boner on the boiler; I threw the switch off last night, and forgot to check to see if there are any leaks this morning.
Oh well, how much can it leak if it is going to? I heard than Burnham's don't usually leak, so we will see.

If you turn off the cold water makeup supply valve, then no more than it holds...20 gallons? But it ain't gonna happen.

 

[maple1]

I don't think I read before - how many in the house? i.e. how much DHW would you really use?

If not much you could make do quite well with a small hot water heater under a counter or in a closet close to where you'd be using it. Or even two, in different places.

 

[firebroad]

I don't think I read before - how many in the house? i.e. how much DHW would you really use?

If not much you could make do quite well with a small hot water heater under a counter or in a closet close to where you'd be using it. Or even two, in different places.

Thought about those little heaters, I don't know how much extra power they will draw. It is just me in the house, and I don't waste much water--and as I say I can always put the kettle on. But lets see what insulation does first.

 

[woodgeek]

IF it is a cheap tank, (EF<0.85) then a hardware store insulation jacket has decent ROI as a simple DIY project.

 

[firebroad]

Its a better one. Bradford-White 40 gal, EF93.

Man-O-Man, what a difference taking a bath or shower! Don't have to fiddle with the knobs as much, I am in and out of that shower in no time, as the pressure is better being located right under the bathroom. Like having instant HW.
I like to take a tub bath once a week. Used to take quite a while to get enough hot water, especially in the winter with a cold tub. Turn water on, wait for boiler to kick on, turn off while waiting to recover, then turn back on. I could read a whole magazine article waiting. Now, I have a hot bath ready as soon as I get out of my duds.