Tankless coil/boiler question

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Old 04-25-11, 07:45 PM
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Tankless coil/boiler question

So I have a 20-25 year old boiler in my home and lately the pressure from the hot water side is less than ideal (about the same as if I turn the cold water on only 1/3 of the way). I'm pretty sure this is because we have hard water where I live in NJ and so over time the coil has undoubtedly built up some scale.

I'd like to replace the coil, since everything I've read seems to indicate that cleaning an old coil is a good way to end up breaking it and/or allowing a leak in from the boiler. Someone came out a while ago to look at the boiler in general and said that it looked like the bolts would snap off and they weren't really willing to touch it.

I took some images of the bolts - if I bought some Liquid Wrench does it look like they would come off ok (without breaking)? ImageShack Album - 8 images

Also, assuming they break, then I'm guessing I'll need a new boiler. What's the proper size for a boiler? The current one is a little over 100,000 BTUs, but my house is probably around 1,300 sq ft with 8 ft tall ceilings. I saw a rough calculation is the volume (10,400 cubic ft) * 5 = 52,000. Since I have a tankless coil the calculation says to add 10,000 so it would then be 62,000. I assume to be safe for heat loss (because my house is old and the walls are not particularly well insulated in spots) and the possibility of expanding my house to 1,500 sq ft at some point in the next few years, then an 80,000 btu boiler should fit both my current and future needs. Does this sound right?

Finally, I know that indirect hot water heaters would be preferred, but I don't have the space for it in the room the boiler is in (which is unfortunately in the middle of the house, so no room to expand in any direction). I also have no basement or attic. They could take a closet located 5 feet away, but it would require channeling through the concrete slab to lay some pipe and the quote we got was about $6k which would have to be about the same price to replace the whole boiler.

Any advice would be greatly appreciated - thanks in advance!
 
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Old 04-25-11, 07:53 PM
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Is there gas in the home?
A tankless coil is about the most expensive way to make hot water. I would figure something out to make hot water differently. Is this a ranch home or two story. I would assume at 1300 sq ft it is a ranch. What about running the pipes through the attic to the closet instead of the floor?
 
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Old 04-25-11, 08:03 PM
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No gas on our street (just all the ones around me... grrrr), so it has to be oil or propane. It's a cape with the attic turned into two bedrooms and a bathroom. So no attic. There is a bathroom upstairs that pipes go to, just not sure how much work it would take to get everything taken apart to get the pipes up and over then back down.
 
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Old 04-25-11, 09:30 PM
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Sounds like my neighborhood... nat gas about 1/4 mile in each direction. No city water or sewer either... maybe we're neighbors!

PB Blaster is by far the best stuff for unsticking stuck bolts. Auto stores, walmart, kmart, HD, Lowes all seem to carry it around here. It really is superior.

Here's what I do for rusty old bolts:

BE PATIENT! TAKE YOUR TIME! The wait will be worth it.

PB Blaster STINKS! so use it sparingly. A few drops goes a long way.

Spritz a little PB blaster around the head of the bolt. A few hours later, spritz a bit more. A few hours later, with a good snug fitting SOCKET WRENCH try to move the bolt just a wee bit... don't try to take it out yet, just get it to move. Even try TIGHTENING it just a very wee bit first... then, spritz another few drops of PB on it and wait an hour or two.

Assuming that you were able to get it to at least move a wee bit, next, you want to rock the bolt back and forth, back and forth... you will feel it start to loosen up. Back it out until you feel it bind up, then back in again. Spritz with a bit more PB... keep doing this until you are able to get the bolt out.

This 'rocking' is easiest with a 'breaker bar' so you don't have to switch the ratchet forward / reverse over and over. You can also use a box wrench if you can fit it in there...

Again, go SLOW! Don't force it! Once you feel it start to bind, run it back in and rock it again. The idea is to work the PB down the threads, and to grind up the rust particles into powder so that the bolt will come out without breaking.

No, you won't have to replace the boiler if you break a bolt, but you may be faced with drilling out the old bolt and re-tapping the boiler. Not an easy task, but it can be done.

As stated by others, the best solution is to find a way to get away from the tankless.

They do make 'stackables' where the boiler sits on top of the indirect water heater tank... might work for you.
 
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Old 04-25-11, 10:16 PM
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Thanks! I didn't know they made stackable ones, that sounds like it would be the ideal solution for me. I'll start looking at prices to see if it's worth doing now since I know at some point I will likely need a new boiler. Do I need to drain the boiler if I'm just loosening and retightening the bolts to the coil? I don't want to do the job myself, just get the bolts loose enough to have someone else come in and do it where they won't be concerned about snapping them off.
 
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Old 04-26-11, 03:39 PM
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Do I need to drain the boiler if I'm just loosening and retightening the bolts to the coil?
Never thought about it... I would think that if perhaps you only did one at a time you might get away with that. Of course you do not want to loosen them all at the same time... but I think you know that! What I don't know is if those bolts go through into the casting or not... they SHOULDN'T ... but if they do and you loosen the bolt, you will have water spraying. Start with just one as a test... and see what happens!
 
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