Heating 24/7 with the Harman but still using the bolier for hotwater

I just put 10 gallons in my oil tank, bled the line and the unit fired right up and ran like it was new. If you exercise your furnace a few times a year and treat the oil in the tank with a diesel biocide, I can't see a downside to letting the boiler sit idle. When I installed my water heater, my box was only 60 amps. I pulled it and installed a 200 amp service. When I put my addition on, I rewired the whole house so the decision to put a new panel in was a good one. The installation was easy because when I replaced my furnace with the Buderus, it didn't have the hot water coils so I just ran the pipes to the new electric water heater and I was done. I also replaced most of the copper pipes with plastic. Much easier to work with than copper. I was nervous about soldering in the walls of my 200 year old balloon construction post and beam house

Yeah, I would leave the boiler as your hot water backup - because an unused boiler will run into issues without regularly being used (think about oil in the lines, etc.). My wife (a Realtor) sees this often when someone has moved out of a house they are selling and it sits for an extended period.

Additionally, I like having the heat backup. I have the thermostats all at 65, but they never trigger unless I forget to fill the pellet stove (which has happened). Keeps the house from freezing. Additionally, if I go out of town, I shut down the pellet stove and let the boiler do it's job.

One gallon of fuel oil is ~140,000btu. Let's say 85% effiecent so 120,000btu

To equal that in electric it would be ~35Kwh. Unless your power is under about 0.10/Kwh, oil is cheaper.

nate379 said:

One gallon of fuel oil is ~140,000btu. Let's say 85% effiecent so 120,000btu

To equal that in electric it would be ~35Kwh. Unless your power is under about 0.10/Kwh, oil is cheaper.

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Empirically yes, however a boiler is never sized for domestic hot water its sized to heat your house. If your not running your boiler to heat your house its not a very cost effective option to use it for making domestic hot water. Now a separate oil burner on a hot water tank thats a completely different story.

nate379 said:

One gallon of fuel oil is ~140,000btu. Let's say 85% effiecent so 120,000btu To equal that in electric it would be ~35Kwh. Unless your power is under about 0.10/Kwh, oil is cheaper.

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At best my boiler is 83% efficient and electricity is 100% efficient. Then if you take into account losses from the system the Electric water heater is still in the 90's and, if it's summer, the oil boiler is only providing DHW the overall efficiency may drop to as low as 33% (I can't substantiate this but I do remember reading it on this forum). Oil isn't a winner.

We have a BoilerMate (Amtrol) 40gal for DHW. It runs like another zone off the boiler. It uses a coil to transfer heat from boiler to the 40 gal. How efficient can this be? Checking prices: 41 gal Amtrol unit is $981 at Bizrate and a 40 gal. electric water heater at Home Depot is around $260. So when the time comes we will probably switch to electric. Have already spent over $200 in new controllers for the boilermate in 10 yrs. Before pellet stove we burned 925gal and now around 400gal. We do run heat on 2nd floor occasionally when it is real cold <15. Curious to know number of gal used for DHW per year. Still have 4 people living here.

Don't get me wrong, I loved all the hot water that comes with the BoilerMate. It's just that the only reason the boiler was running, for me, was to heat the hot water. If the boiler is running anyway to heat the house, then sure, I can totally see still using it.

What difference if the boiler runs for hot water or a regular water heater? Other than the few gallons of boiler water that has to get heated?

This is on my radar as well, but i'm concerned that if i shut the boiler off, my basement will get REALLY cold and i may have freezing pipe issues. my basement is only half below grade (back side and 1/4 below grade (front side). Anyone else in this same boat? With the boiler on, this area stays about 60 in the winter. Frankly, i think I want BOTH, I want the electric AND the boiler. The electric for summer, the boiler for winter as it still runs 1 level of my home (below stove grade, i have a 4-level split level, stove is on level 3 of 4, level 2 is oil-heated, level 1 is the basment)

And the cast iron. I don't know, but I was using ~.5-.75 gal of oil per day, near as I could tell, just to heat water in a 40 gallon BoilerMate for 2 people. Assuming, .5 gallons and 365 days (since I don't heat the basement the joists are insulated) and $3.85 / gal for oil, it's $700/ year for oil. At $.10 /kwh (AFTER the basic service charge, which of course is a crock, but it' the minimum) that'd get me 7000 kwh a year, or, like 580 kwh/month. You can heat a lot of water with that juice.

I guess one has to figure out the actual amount of oil used to just heat water; I tried, but admit could be wrong. Also, I could drink a couple less sodas a day and come up with the same savings.

I just purchased a Harman Hydroflex 60 boiler and am looking for anyone who also has this boiler to share ideas on it's functionality. I'm using it as a primary heat source with an oil backup. I've been trying different pellets and different feed rates to keep it at it's highest efficiency but am still using more pellets then I originally thought I would. Thoughts please. Thanks.

thro9 said:

I just purchased a Harman Hydroflex 60 boiler and am looking for anyone who also has this boiler to share ideas on it's functionality. I'm using it as a primary heat source with an oil backup. I've been trying different pellets and different feed rates to keep it at it's highest efficiency but am still using more pellets then I originally thought I would. Thoughts please. Thanks.

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I suggest starting a new thread youll get additional readers. Also provide house size, insulation amount, how much oil you burned before would be very helpful.

nate379 said:

What difference if the boiler runs for hot water or a regular water heater? Other than the few gallons of boiler water that has to get heated?

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Boiler never runs at full efficiency when heating water indirectly. You have the times when boiler is not running (Losing heat through stack / area) and then you have to get it up to temperature to begin efficient heat transfer to the domestic water. That adds up to wasted oil, as bad as 20-30% efficiency depending on your situation. I'm still using my boiler for hot water, only because I like having a working back-up, and I don't like the idea of leaving it idle for years.

Electric water heater is extremely insulated, has little to no heat loss, and runs at 90%+ efficiency. So while per BTU it is almost more expensive, it is so efficient that it usually is cheaper in the long run. Not to mention maintenance costs, fuel delivery etc etc...

Do you have a source for the 20-30% or is that just a guess? My Google fu is coming up with numbers around 60-90% combined, all depending on what the equipment is.
I'm certainly not an HVAC/plumbing pro so I really don't know.

"INDIRECT WATER HEATERS
This type of water heater uses the home's boiler or furnace as the heat source. When used with a new, high-efficiency boiler or furnace, an indirect unit is usually the least expensive way to heat water."

My house is "all gas". I spend about $35/month in the summer. How much of that is just from the boiler running to heat water and not the kitchen stove or the dryer, I have no idea.

TheMightyMoe said:

Boiler never runs at full efficiency when heating water indirectly. You have the times when boiler is not running (Losing heat through stack / area) and then you have to get it up to temperature to begin efficient heat transfer to the domestic water. That adds up to wasted oil, as bad as 20-30% efficiency depending on your situation. I'm still using my boiler for hot water, only because I like having a working back-up, and I don't like the idea of leaving it idle for years.

Electric water heater is extremely insulated, has little to no heat loss, and runs at 90%+ efficiency. So while per BTU it is almost more expensive, it is so efficient that it usually is cheaper in the long run. Not to mention maintenance costs, fuel delivery etc etc...

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Sorry I can only source other people I know based on fuel usage when NOT heating their home with their boiler. There have multiple threads in the forum in regards to this too, with the same general consensus.

And even 60% efficiency with oil isn't very promising =)

It's actually a very hard subject to Google foo, but most people that have run the system, understand the downfalls.

Indirect water heaters are very efficient, especially if your using the boiler for heat at the same time.

That efficiency goes out the roof in the summer or if you are not using the boiler for heating.

Furnaces do not usually heat water...

SUMMER / WINTER with stove
So to get/keep the indirect water heater satisfied, I have to heat the boiler to at least 140* (To begin transferring heat to indirect water heater) and get it up to 180+ to be efficient. Then the indirect water heater get's satisfied at 120 - 130 - 140 pick a number. Then you have the boiler + loop sitting with heated water going to waste, especially in the summer. So... If a household takes 3 separate showers, runs the dishwasher, runs the laundry, that's at least 5 cycles. If the boiler had time to cooldown, it will have to heat up whatever liquid is in the loop to 140-180 before it starts transferring heat (Mine is probably 10 gallons 6.6 in boiler 3 in piping) By the time this cycle is complete,you've heated 30-50 gallons of liquid repeatedly, just to transfer heat, which can easily be 20-50k BTU+ worth of fuel that ends up heating your house instead of your water. On top of that, many people have to leave their boilers with a low limit, meaning the boiler is short cycling 5-10 times a day, in addition to the times it has to start up for the indirect.

WINTER-
IF I am heating the home in the winter however, the water is always hot, so it runs just about as efficient as the boiler does.

I will probably use 250-300+ gallons of fuel just to heat my water this year, so around 1000$.

I miss being on cheap gas =/

I have the same setup, and use about the same amount of oil just to heat hot water. I am switching to electric!

Ernest Smith said:

Now that I use my stove for heating the house I want to stop using oil altogether. I have a 25 + year old boiler and it still runs to heat water. Has anyone by-passed the boiler and hooked up an electric water heater instead? My plumber tells me that a stainless steel tank used in conjunction with my boiler would cost $1,800 installed. I don’t want to spend that kind of money and don’t want to use oil.

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Installed a 40 gal energy efficient electric water heater 6 years ago. Had an oil burner FHW with domestic water coil. Just 2 of us but with daily showers, laundry, dishwasher electric has only gone up about $20. Saves big, big time compared to running the boiler 24/7 on oil. Heat totally with pellets and wood. Turn the boiler on once a year to check it out and no issues.

Heater very easy to install all you need is 240 breaker. No big deal. I've recommended this too many and of those that did all were extremely satisfied.