Question regarding an old hot water system


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Old 02-22-07, 07:28 AM
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Question regarding an old hot water system

I'm buying an older house as another fix up project. The house was built in or around 1900. It currently has a single zone forced hot water system with cast iron radiators, and cast iron baseboard. The boiler is older, prob close to 20 years and has a domestic coil for domestic hot water. The pipes look to be cast iron as well and are not insulated for what I can see. I already plan on replacing the boiler due to it's age and putting in a separate hot water tank or on demand hot water heater. What do you guys think about the rest of the system. I am having the house inspected this weekend, so I don't have details regarding the condition of the system yet. I'm told it works and doesn't leak. The house is 2000sq ft. I can't imagine the system is that efficient. It looks like a hodgepodge. The baseboard is in what I'm sure was a later addition. I have people telling me that the old cast iron radiators and baseboard units are very efficient at holding heat and a steady comfort level, but I have my reservations. Epically the one zone thing. Are there any other ways to modernize the system without incurring a lot of cost. If it gets too expensive, I'd rather rip the whole thing out and duct it for forced hot air and central air. Any ideas.
 
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Old 02-22-07, 08:49 AM
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Cast iron rads and cast iron baseboard are good. Keep them.

If the piping to the addition is reasonably laid out, even if a hodgepodge near the boiler, then zoning the house into two shouldn't be too hard. Use separate circulators and a switching relay, or zone valves and a zone valve control.

For DHW, I would suggest an indirect hot water heater tied to the boiler rather than a separate heater or on-demand system. Neither has the performance or efficiency of an indirect.
 
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Old 02-22-07, 10:08 AM
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Awesome. Thanks for the info. You know, before seeing this boiler, i never even knew about a domestic coil. Do you have or know of where I can find info on them. When I replace the boiler, I will now most likely keep the domestic coil.
 
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Old 02-22-07, 10:22 AM
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After doing a little research, I'm seeing that a domestic coil and a indirect system are different. The system now has a domestic coil. No tank. When I replace it, should I stick with the domestic coil, or switch to an indirect tank. Also, does using a system like this mean that the boiler will fire up even when heat is not called for to provide domestic hot water?
 
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Old 02-22-07, 11:00 AM
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I'd love to see some pictures.

Whatever you do, don't "rip the whole thing out and duct it for forced hot air" as it will never be as efficient or as comfortable as the hot water.

Absolutely go for the indirect domestic water heater. Boiler-immersed coils are a cheap method of supplying hot water for domestic purposes and rarely provide more than a bare minimum. Yes, the boiler will fire to supply hot water but the boiler will be far more efficient than a domestic gas or oil fired water heater.
 
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Old 02-22-07, 01:43 PM
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Here is a pic



I'm not sure how old the boiler is. Looks like the second one, maybe third, and the house is over 100 years old. My inspection is not till Monday so i'll know more then. This one is oil, but when I replace it, I'm going to NG. I was considering a Mod/Con unit after doing some research. One had a domestic coil that was supposed to deliver 5.5gpm at 110f. Maybe the indirect will be better? I guess I'm going to have to have a pro check it out and advise. I'm not sure about zoning or the whole primary/secondary loop thing.
 
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Old 02-22-07, 04:12 PM
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wow... that chimney looks like it needs some attention! You may need a liner in that flue if there isn't one already, no matter what you do. Insist on a thorough inspection of the chimney.

I'd guess that was once a steam or gravity system, converted to forced circulation at some point...

Is the slab around the boiler badly soaked with oil ?
(that dark patch...)
 
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Old 02-22-07, 06:21 PM
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Indirect

An indirect is far superior to a tankless coil in both efficiency & quantity of hot water.
 
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Old 02-22-07, 07:54 PM
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Yeah, that chimney looks a bit tender at the base.

It is possible that this was once a two-pipe steam system but I kind of doubt it. The piping is quite possibly wrought iron and if so would likely be in excellent shape. The fittings look like cast iron. There may be some general corrosion of the piping where the copper was installed, it would require disassembly and internal inspection or at the very least an ultrasound examination.
 
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Old 02-22-07, 08:18 PM
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On the plus side, it looks like a pretty easy re-do of the near-boiler piping and zoning. If the chimney's shot, do you have access on another wall for a direct vent boiler? What's the cinderblock wall? The addition?

This reminds me of a friend's 1830 house. Bad chimney that couldn't be reused, but they got a direct vent boiler through one of the biggest sill timbers I've ever seen. Good thing because the foundation is all granite boulders 12-14" thick.
 
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Old 02-23-07, 05:25 AM
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When I have the inspection done, I will be there with the inspector, and will insist he check that chimney. One of the first things I was going to have done was a chimney cleaning anyway. They can probably tell me the condition of the inside better then the home inspector. That block wall is the foundation for the addition. If I do decide to go with a modulating/condensing boiler, they all seem to be direct vent PVC systems, so I could just pipe them right outside the wall. If the chimney is usable, can you pipe direct vent systems right into the chimney, well at least the flue gas. Obviously not the fresh air. Thanks for all the input so far.
 
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Old 02-23-07, 08:01 AM
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If you go NG, why not get a M-C boiler and use the chimney as a chase for the PVC flue (and intake too if there's room enough)? That eliminates much of the hassle of sidewall venting (clearances, ice formations, etc.).
 
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Old 02-23-07, 10:16 AM
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That's what I was thinking. Definitely would like to go with a M/C boiler. I never thought of just running the PVC through the Chimney. That's a good idea. Oh and NJ Trooper, that dark spot is a shadow. I have a large lens on my camera, and didn't bring my flash. I had to use the puny built in one and it doesn't clear the lens. The floor isn't in bad shape for it's age.
 
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Old 02-26-07, 10:11 AM
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One last question. When I re-do this system, I want to add a zone for the finished Attic, which right now has electric baseboard. Can i use PEX tubing? I'd hate to have to run copper all the way up there. I think it would be much easier to run flexible pipe up the walls. Just wasn't sure if this was for lower heat domestic water or if it would cause any other problems.
 
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Old 02-26-07, 10:20 AM
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PEX would work fine.

Just be sure to factor in the height of the attic to your system pressure.

(highest point above circulators / 2.31 + 5psi)
 
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Old 02-26-07, 12:24 PM
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Will do. Thanx
 
 

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