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boiler pump opperatios?

Started by stumper, September 30, 2009, 03:09:44 PM

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stumper

OK my boiler heats the hose well and I love not shipping my money to the middle east.  Now I would like to slow the rate of the money I am shipping to the power company.

I have a pump on my boiler that runs continually, and that seems like a waste to me.  I would think some smart guy could design it so the pump only runs when there is a call for heat in the house.  Cold start boiler systems do this with the oil burner so why not apply the same logic to the OWB circulator pump?

If for some reason that would not work then could something be installed to opperate the circulator pump at different speeds?  I have a three speed pump already so I would just need a way to tell it to run slow when there was little or no call for heat and high when there was.

Since this concept is incredibly obvious I am sure that someone has either already done it or it can not be done for some reason.  So what do you guys think?

beenthere

Wire the pump to the thermostat (the one that will call for heat) and try it out to see what the delay might be.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

bandmiller2

Stumper,what do you have for a circulator pump,those little Taco's and their ilk don't use squat for power.The less cycling on and off the better for outside boilers less smoke and creasoat buildup.more even heating in the house.The pump is just the cost of doing business,many outsiders will overheat without circulation.Frank C.
A man armed with common sense is packing a big piece

tonto

I have to agree with Bandmiller2, I have not noticed a very big increase in my electric bill and my OWB runs all year. My plumber told me that my pump will last longer if it doesn't shut off. The start up is what's tough on the little pumps. Tonto.
Stihl MS441 & Husqvarna 562XP. CB5036 Polaris Sportsman 700 X2. Don't spend nearly enough time in the woods.

MudBud

Since the inception of the 2300 my electric bill has increased by $30-40 per month.  I talked with others that have seen the increase as well.

stumper

I see my electric bill go up about $25.00 per month when I fire up the boiler.  Some of that may be increase the increased use of the circulator pumps in the house.

Yup, I am sure that starting the pump causes increased wear and stress, but that does not mean it should be left running all the time.  Starting causes accelerated wear when you start your car or truck but we do not leave them running.  The break even point on leaving an engine running vs. the wear and tear on the enginge for both gas and deisel engines is measured in seconds.

I struggle to beleive that with a capacity of 450 gallons in my outdoor wood boiler (eclassic 2300), that the additional circulating in the pipes and boiler are needed to keep the boiler from overheating.

Now if someone say that the cost of the installation of the sensors, relays, ect.  would so out weigh the savings I could understand that.  However, considering the pay back time on my boiler is about 8 years, I have to think that a system could be installed with a similar or shorter pay back time.

Again there may well be a reason, but it could be that they figure we save enough on oil we should not care about wasting money on electricity.


James P.

hi Stumper , I am thinking of building my own owb, and always thought they would only be running the pump when called for. very good question . I had no idea they ran all the time.If it raised my electric by 40 dollars I would be paying 2x as much as I am now . I only run a freezer during deer season and until the meats gone, because I don't like the 15 bucks a month increase in my bill. so 25 to 40 would really make me think twice about it. Guess I will stick with the old woodstove for now.
                James P.

PineNut

I run the pump on my OWB only when heating is called for. The only disadvantage is there is a delay from when the blower starts up and when the heat is delivered. Get a blast of cool air at first. But I plan to continue operating it that way.

I just checked a couple of pumps I have. One is rated at .4 amps and the other is 1.4 amps. At .15/kwh, that figures out to about $5.25 and $22 per month to operate these two pumps full time.

JSNH

I have an outdoor boiler and the pump is on all the time it is less than 150 watts. But 150 watts is $16 a month. I think it runs more than necessary but you also need to mix the water in the boiler to reduce hot spots. Taco makes a pump controler that takes plug in expandable cards and one is the PC610 pump exceriser card. The exerciser card does from 30 seconds to 4 minutes on and from 5 minutes to 2 weeks off. I think a 2 on and 5 or 10 minute off would work. It's on my to do list.

bandmiller2

Sometimes its hard to get a good handle on elect usage.Cool weather is when most of us fire up which also coinsides with shorter days and more lighting demand.Heating and cooling is not good for any boiler especially welded steel.The more even the temp the longer the boiler life.With proper plumbing and the right elevations natural convection could be used to circulate enough water to keep the system at an even temp using the circulator pump only when the thermostat calls.Most of the folks that truely understood gravity and natural convection heating are now living with God.Today you just force the water with a pump, elevations be DanG ed. Frank C.
A man armed with common sense is packing a big piece

Hilltop366

Quote from: PineNut on October 01, 2009, 09:58:31 PM
I run the pump on my OWB only when heating is called for. The only disadvantage is there is a delay from when the blower starts up and when the heat is delivered. Get a blast of cool air at first. But I plan to continue operating it that way.

A simple in line low temp cut off switch (high voltage) would stop the blower from turning on until the system is heated up.

Other things on most systems use power even when the heat is not on, like low voltage transformers and electronics.

I geared my Tarm wood boiler using only 110v switches and thermostat it has a hyd draft control that does not use electricity, my entire heating system only uses power when the circulator is on (calling for heat or dumping heat) it draws 0.95amps.
I do know it is better to run at a constant boiler temp. but in my case it adds up to a lot of wasted wood an open windows if the boiler is run all the time (radiant in floor heat) so what I do unless it is very cold is lite a fire at supper time and pump the heat in the floor, fill the furnace once if it is not too cold more times if it is colder this saves a lot of wood and does not cause a lot of creasote because the boiler does not idle much.


JJ

I would worry about freezup in the pipe running from OWB to house.
On my system here are couple of places where air can get under the insulation packed around the water line.

last year, I run out of wood (end of Feb), but had to keep the circulator pumps running to keep from freezing; but I would like to put my wrap-around pump (house side of heat exchanger) on a thermostat.  I have one more zone on my heater control box, but would need to add a aquastat to the water tank in the boiler.  I would like to keep the water around 50F.  With both pumps running, and no fire in OWB, the water temp stayed at 150F from heat exchange running backwards.   I did not see my oil furnace run any more than normal, so the stored heated water outside did not seem to pull down the system so maybe not real concern.  I also have 3 speed taco pump, so I did slow down the pumps to lowest setting.

One thing I did with my e-classic 2300; is to rewire the outlet on the unit, so I do not have to have the unit on to have power to the outlet.   This will fix the problem with the 2300 running the blowers last year; because the lowest water temp setting is 150F on my unit.

I mostly did this so I could plug in my mosquito magnet this summer.  The mosquito's loved to hang out at the OWB I think from all the carbon; and was easier than burying the power cord.

        JJ

red oaks lumber

i like the pumps running all the time, if the fire goes out atleast my lines are still flowing. northern wisc. winter is dam cold, you guys talk about 20.00 electric bills with pumps running , true but getting your domestic hot water saves way more electicity than the pumps running, also burning wood is cheaper than gas or oil so you save thatway .
there is noway to heat your home or shop for free, just cutting wood costs something,for me when i was using gas, my bill ran $3,500 per year @.60/ gal heating with wood my wood costs $1600/ yr plus i keep it warmer than before. like some one said its the cost of doing buisness
the experts think i do things wrong
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wi woodcutter

I was told that you have to keep the pumps running all the time, or you will get hot spots in the stove. I have quite a bit of money in my stove, so I think that the cost of running the pumps is better then messing up the stove.
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stumper

JJ, I also had to wire an outlet prior to the switch.  Seems foolish that Central Boiler would switch the outlet.  In my case I went away for a winter vacation and it seemed stupid to blow cold air through the boiler that I was heating with oil.

As for the need to run the pump to keep the boiler from developing hot spots, that seems a stretch.  Water is a conductor of heat and natural convection would move the water in the boiler even without the pump.  If we ran the temperature of the boiler closer to the boiling point I could see the concern but not at the 185 where it comes from the factory.  However, for discussion sake thats assume it is a problem and then switch the circulator pump could be told to come on when ever the fan was on calling for heat (could even time it to go off 15 mins. after the fan stops).  That should address any hot spot issues.

As for running the pump to maintain a constant temperature in the boiler.  That is not a concern for me as my oil boiler was designed as a cold start boiler.  I guess that could be a concern for older boilers.

Not running the pump could allow water in the pipes to freeze.  Again in my case I would hope to not have that issue.  I installed my lines 4 and a half feet deep with extra insulation around the thermopex.  I have found here in central Maine that frost does not normally penetrate more then 4 feet as long as the area is not plowed.  If we have a snowless winter I think the insulation will keep my pipes from freezing.  This only leaves the pipes at the boiler in jeopardy.  I have insulated those and the heat of the boiler seems to keep those warm.

I do not run my outdoor wood boiler in the summer, but if I did the $25.00 in electricity would cost me as much as the 10 gallons of oil it take to heat the water, and I would still be using wood which has a labor cost.

pasbuild

My pumps are both controlled by thermostats, the one in the shop is a simple line voltage stat and I have the one in the house wired to a low voltage switch that turns on the line voltage to the pump. This was done to allow the furnace  to function as a dual fuel system.
If it can't be nailed or glued then screw it

jorge016

The taco pump on my Central Boiler runs 24/7.  The pump in the house only runs when the home thermostat calls for heat.  I was concerned about the energy use so called our electric co-op and put a meter on the taco pump to measure the energy consumption.  It used as much power as a 75 watt light bulb.  We use our boiler all year round to heat our hot water and have saved about $60/month.

twodeep

When I lose electricity for a day or more, my Central Boiler CL40 does indeed overheat to where the water starts boiling.  I even tried covering around the door etc. with duct tape to keep air out but to no avail.  So I conclude that you do indeed need to keep your circulator pump running at all times.

solidwoods

It would be nice if you gave a little more info in your bio. so we know if we are talking about Tijuana cold of Toronto cold.

If you stop the water in the feed and rtn line it is now subject to freezing.

Calculate the cost of the pump and let us know.

What size pump do you have?
I have a 300' line and run a 1/25th hp pump and our elec. rate is $.08kw.

If you want to save some $ with a wood fired water heater, clean the sludge out of the bottom of it every 6mo. and replace/add more anode.
jim
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stumper

Central Maine cold.  Coldest temp in an normal winter is 30 below, but most of January through Febraury average is probably10 degrees at night 25 during the day. 

There is little chance of freezing as I installed the pex 4 1/2 feet deep and added additional insullation.  Normal frost depth is 4 feet for un-plowed areas.  The domestic water runs at the same depth without any issues.

superwd6

Cold start oil boilers are a thing of the past. More efficient designs have problems  with condensation rotting out your oil boiler in five years or so. Sulfer in the oil is the big problem. Thats also why you don't see many hi efficient condensing furnaces in the oil industry, most of them have holes in them within a few years. Most boiler manufacturers of oil boilers call for Primary-secondary loops using two or more pumps. anybody not considering an outdoor boiler over a .75 amp draw isn't looking at the big picture.    Mark

stumper

My teen age step kids think I am a thing of the past as well, so you have company Mark.

Just for referance I already have an outdoor wood boiler tied into my 18 years old cold start oil boiler.

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