Oil Furnace - No hot water. What to do?


  #1  
Old 12-29-03, 08:15 PM
Kongar123456
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Question Oil Furnace - No hot water. What to do?

Hello all,

I've gotten some very good advice in the other doityourself.com forums, but this is my first post here in the heating section. I'm hoping you guys can offer some advice.

I've bought a new home recently, and the hot water situation has gone from bad to worse. Oil furnace - 4 heating zones, 1 "hot water coil." The furnace is running at 87% efficiency, and I have no other problems besides what the service tech said was a bad coil. The problem is this: I turn on the hot water, I get maybe a few gallons of scalding hot water, and then I am taking a shower with essentially New England well water - brrrrr Once and a while, the furnace might actually kick in, and I may get a luke warm shower - this happens maybe once a week if I'm lucky...

I read 10 pages of posts and didn't see the answers I was looking for, so I figured I'd start a thread. I apologise in advance for my ignorance

First question - educate me please
I really know nothing about furnaces, but I am a chemical engineer, so I can take a guess as to how it works. The furnace (oil flame) boils water in a boiler, the steam travels to the 4 heating zones of the house, condenses in the radiators, and then returns to the boiler (or drain). Inside the boiler is this "Coil" that has supposedly gone bad. This coil acts as a heat exchanger between the steam in the boiler and my cold water inlet, thus producing hot water for my house on demand. Do I have it right?

#2
I'm faced with a choice. Replace the coil - $600. OR bypass the coil and install a hot water tank - $1600. The hot water tank works like another zone in my house? Heating coils inside the 40gallon tank acting like my radiators? Thermostat on the tank hooked up to a 5th zone, having a setpoint of my choosing (150ish)? Am I understanding my options correctly?

#3
How often does a coil fail? Since I'm on a private well that has hard water (Iron and calcium deposits), and is prone to puking sand into my house, I'm thinking that replacing the coil is going to be a exercise every few years. My other concern is that I've heard that this method of heating hot water cannot keep pace with the demands of a modern household. Is this true?

#4
On the flipside, $1600 dollars seems like an awful large amount of money for essentially a 40 gallon hot water heater. I had a condo before, and I had a natural gas hot water heater replaced for about $500. I see less plumbing work in my new house than they had to do in my condo. What is so pricey about doing it with oil? Is it because they need to add a zone to my furnace as I've speculated above?

#5
What causes the coil to fail such that the same failure won't happen to a hot water tank? Does no new water enter the boiler? They offer a lifetime guaruntee on the hot water tank, so I'm inclined to believe them when they say the hot water tank will last 20+ years. Why is this so?

#6
Is $1600 for a hot water tank (installed) too much? Should I call a heating and plumbing professional, or leave it to the oil company? My oil company by the way is Petro oil...

What do you all think? Replace the coil or install an oil based hot water heater?

Thanks,
Kongar
 
  #2  
Old 12-30-03, 10:21 AM
Ed Imeduc's Avatar
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Location: Mountain Williams Missouri
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Lightbulb Hot water

You said well and hard water. Have you tried to just clean that hot water coil there in the boiler of the lime and calcium that builds up in it over the years . Also Id put a water softener there before the water goes in to the hot water coil and the home.

So get some chemical's and clean it out.

I dont think you have steam heat there.Do you have a low water cut off on the boiler, or a water gauge? It could just be a hot water boiler.

If you did want a hot water tank Id get one thats all its own.
You can get a oil fired hot water heater that works just fine and has not a thing to do with the boiler there. ED
 
  #3  
Old 12-31-03, 06:29 AM
D
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I have basically the same oil boiler/tankless (coil) water heater set up.

See my post:

http://forum.doityourself.com/showth...677#post371677

where there is a discussion on how I cleaned my coil when the pressure became very low for hot water.

However it seems your burner may not be coming on when it should - your use of hot water in the shower should lower the boiler temp and cause the boiler to start up to give you hot water. This may also be an area to expolre. Others in this forum can answer more precisely but I believe any adjustment to be made for this would be at the aquastat.

With my system we never run out of hot water. Good luck with yours.
 
  #4  
Old 12-31-03, 01:15 PM
Ed Imeduc's Avatar
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Lightbulb Hot water

Could be your coil in the boiler is also dirty on the out side of it. could you pull it and clean it? Try the inside of the coil first
 
  #5  
Old 01-02-04, 03:51 PM
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You were mostly correct in all your statements about how you percieve you system to operate. Hopefully you do not have a steam system but I would like you to verify that for me. If you have steam and more than one zone, your zone valves and connected pipes will probably be very large. Also you will have the low water control Ed mentioned and a sigh glass tube to show you the water level. Let me know what you have.

I would recommend the investment in the storage tank because it takes the 'instantaneous' out of the 'instantaneous coil'. Look into a Phase III tank. It is more tolerant to hard water conditions and possibly a little more expensive. Most indirect tanks today are made of stainless steel which costs more but will last almost forever.
 
 

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