Saved oil this year -- but not enough. Why?

[mrjohneel]

Installed my pellet stove in mid-January and due to this crazy warm winter, I only used one ton of Barefoots and other brands until today. The goal of cutting oil use has worked. But here's the question:

My boiler still runs to heat my hot water. So during or after running the sink or dishwasher, I can hear the boiler kick on. That makes sense. But why does it kick on at other times to heat the water? For instance, with no water running (dishwasher, clothes, sink) it will come on for a few minutes in the middle of the day. It's not sending heat to the radiators; it's definitely related to hot water.

I guess I don't really understand how the system works. Apparently I don't have a true "on demand" system where the burner only fires when I need water. Does it run to keep hot water in the pipes when I'm not in need of water? Just FYI, I don't have a water tank -- just the furnace/boiler firing to heat water when I need it. Any way to reduce my oil use even more? Thanks in advance.

 

[Ejectr]

There is always heat loss from the boiler water just sitting there. Your aquastat on your furnace controls when the burner comes on to heat the water in the boiler...not the hot water coil in the boiler resevoir. The hot water is just a by product off the heated water in the boiler. Cold water runs through the hot water coil and is heated by the heat in the boiler water. The burner is not heating the water in the hot water coil directly. It's conducted to the coil from the heat in the boiler water.

Your boiler will cycle on/off all summer in relation to the aquastat settings. Usually 160 low...200 high and a differential of 20 degrees. So your boiler will come on at 160 and turn off at 180.

 

[lessoil]

Not an expert but this is what I think is going on.
There are 2 types of boiler setups: One is cold start and one is hot start.
One keeps the boiler at or above a minimum setpoint. (Yours?)
The other type will actually allow the temp to fall when not in use. (Ours)
Ours will come on to heat our water via a 40 gal. Boilermate or if the heat
is turned on. Otherwise it is quiet.

 

[nailed_nailer]

In simple terms.
Your boiler maintains a reservoir of hot water there for your immediate use.
When you open the kitchen (or bath) faucet the hot water is there quickly.
Your system (as described) does not instantly heat the hot water for use.
When you open a faucet for hot water you draw from the maintained hot water reservoir.
The boiler replenishes the reservoir with cold water and brings it up to whatever the set point is set to.
You can run out of "hot" water if you use more heated water than the reservoir holds.
i.e. the kids taking a long shower.

Also, when the reservoir is just there in standby (waiting for you to open a faucet) the boiler will periodically RE-heat the water in there so that you have hot water available.

Think of the reservoir as a battery. You deplete it as you use hot water (showers,dishes, washing the cat, etc.) the boiler re-charges it as needed.

That is why insulating the hot water pipes, putting on a thermal blanket around storage tanks, and having heating units serviced regularly all help in keeping the heated water at useable temps longer. Means less cycling of boiler to keep the Tank (battery) charged.

Hope that helps.
---Nailer---

 

[Ejectr]

You don't draw hot water directly from the boiler reservoir. There is a coil that sits in the resevoir that cold water goes through and is heated for hot water. The two are seperate. That way if you want to put anti freeze in the boiler water to keep your pipes from freezing, you won't be drinking it.

 

[daveswoodhauler]

I ran into this same situation as I have a "warm start boiler" and was frustrated with my oil use during the summer time with the boiler kicking on every few hours or so. I was thinking about going to an electric hot water tank as the cost would be much cheaper to run than with oil, but in speaking with a few boiler techs and folks on this good board, they advised against it as the problem with the warm start boilers are that the seals can go bad when the unit is shut down for an extended period of time and stays cold, then is fired up in the colder months. Although I don't have a pellet stove, my oil consumption dropped from about 750 gallons per year to 450-500 or so with the wood insert, but the problem is that about 50% of my oil use is just for the hot water. I'll be looking at a much more efficient setup when this boiler kicks the bucket, but for right now I am stuck.

 

[mrjohneel]

Thanks Nailer, and all. I get it now. (I still hate the sound of oil burning!)

 

[peakbagger]

A good way to descibe a hot start boiler is leaving your car idling in the driveway all year round, in case you want to go driving. I figured with my tankless coil boil I used to burn about a galon per day. I put in solar hot water and shut down the boiler for the summer and heat my water with wood in the winter

 

[JustWood]

I wonder if a HD timer like the ones installed on water tanks wood work on the aquastat.

 

[gobuck]

I put my furnace on a switch that I turn on if my solar hot water system hasn't made enough hot water. I filled my tank in October and am still reading 3/4 of a tank.

 

[SmokeyTheBear]

You might be able set the upper limit on the aquastat down, plus insulate any tank and the piping leading to the tank from the boiler and piping leading from the tank to the rest of the hot water faucets.

 

[DexterDay]

Yep... Insulate. Insulate. Insulate. Drop the upper temp down (if possible).

Or go electric hot water heater route and put boiler on a schedule so the seals dont blow (as above poster stated). I know very little about boilers. But I know I got my pellet stove to reduce my LP consumption. Went through 3-4 tanks a yr when using LP furnace. Im at 2.5 yrs since my last fill and still about 45%. I cut my LP consumption 100% for heating. We still use it for cooking. But filling the tank once every 4 yrs, I can handle.

To keep using that much oil and using pellets (added cost), I would definitely look at different avenues. I used 4 tons of pellets w/ the Quad for the 1st few yrs. With the addition of the wood stove last fall (and pellet furnace), I only used 2 ton of pellets.


Heated the house for about $400 this year (not counting my time spent C/S/S wood and all needed equipment). To go from $4,000 a yr to $400 a yr.... I wont go back to LP until my health, age, etc deems it necessary.

Lots of intelligence on this board. Hopefully there is a cheap and simple solution to your problem. Its all about the buck $$$$$$.

 

[Brokenwing]

Electric Hot Water Heater is the way to go. A friend of mine heated all his domestic hot water with his boiler, and he bypassed the coils and put a hot water heater in. Sure electricity costs money, but a heck of alot cheaper then using oil to heat your water.

 

[SmokeyTheBear]

Electric Hot Water Heater is the way to go. A friend of mine heated all his domestic hot water with his boiler, and he bypassed the coils and put a hot water heater in. Sure electricity costs money, but a heck of alot cheaper then using oil to heat your water.

Make sure your electric rate is not through the roof for this use. Some places electric at 100% efficiency is a poor replacement for oil at 80% or higher.

I keep checking and at the moment it is a no go for me.

 

[gerryger]

I HIGHLY recommend a Siebel Eltron tankless on-demand electric water heater. Only uses electricity when in use and I never run out of hot water. Heating my DHW with my OIL-fired boiler was a complete waste of money. The purchase of this water heater along with my pellet stove has reduced my oil consumption dramatically. I actually believe the water heater is saving me more money than the stove because of the fact that DHW is needed year round.

The savings are huge if you are using an oil fired boiler. The savings compared to a standard electric hot water are not as huge, however it is still more economical to go tankless.

 

[katman]

As said above, your aquastat is kicking your boiler on to maintain set temp. You can lower the temp, but you will still be wasting money on oil. Unless your electric rates are really high, a good, efficient water heater will be cheaper. I've shut my boiler down completely every summer and never had a problem with leaking. Unless you have demand for a lot of hot water, you can even put the hot water heater on a manual switch or a timer. Have it start a few hours before normal time for showers and then shut off during low use periods. Water will stay warm in the tank for a long time with the modern electic water heaters so you would have plenty until the next warm-up cycle.

 

[Dougsey]

gerryger, Curious as to what model Stiebel you have? Those units draw some serious power! I only have 100amp sevice so I don't think it's doable.

 

[bill3rail]

Have it start a few hours before normal time for showers and then shut off during low use periods.

My Oil Burner runs for about ten minutes after it has been off most of the day.
The oil consumption was bothering me when it kicked on to heat the supply when there was NO demand for hot water.

Bill

 

[gerryger]

gerryger, Curious as to what model Stiebel you have? Those units draw some serious power! I only have 100amp sevice so I don't think it's doable.

I have the Tempra 24 Plus which has 2 heating elements thus the need for (2) 60 amp feeds. You will need to run 6 gauge Romex which can be pricey. My runs weren't that long. I made sure my unit was relatively close to the electrical panel. You are correct...100 amp service is not doable....200 amp service is required. I was lucky...about 5 years ago my electrician talked me into upgrading my electrical service from 60 amp to 200 amp. I was going to go with 100 amp. Glad I listened to him.