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jackieo · Oct 8, 2008, 08:34 AM

Have two ancient oil heated boilers in hundred year old house. House is separated into duplex. Want to switch entire house to one boiler system on gas. Have received quotes, "it'll just cost you 400 bux for extra piping" to "you need a hydronics expert to map out yadda yadda, 10 grand.
Can someone tell me if it's really that complicated to switch from two to one? I don't know if I'm coming or going anymore because to the incredible disparity in quotes.
Thx
Jackie:eek:

EPMiller · Oct 8, 2008, 03:58 PM

How many zones on each side of the house? If you don't know that, how many thermostats? Without knowing anything about the system other than that it's old, I really can't say if it is $400 of piping or MUCH more. Copper isn't cheap and iron pipe is a lot of work! If they have to take the lines through a thick masonry wall or something like that it will cost more. Also you might have the issue of maintaining a firewall to deal with. And they will have to retrofit insulation if you want a good job. If the current install is a rats nest or undersized, that will have to be fixed too.

Someone will have to calculate the heat load and decide on the size of furnace needed. If it starts to get really large it might be better just to replace each one individually. Remember, when you go to one furnace, if that one breaks down there's NO heat anywhere. Get references on any contractors that you get estimates from. Where I work they had used a contractor that just shot from the hip when he did an install and we have some really oversized furnaces that are problems. It is worth paying for someone to do the work correctly the first time.

mygirlsdad77 · Oct 8, 2008, 04:12 PM

If the new single boiler is sized correctly and there is not any problem with the existing piping(meaning the only problem is the current boiler) then it would just be a matter of pump(or zone valve) placement and size, and tying it all together at the new boiler. Also may need some check valves installed depending on what your current setup is. I would say four hundred sounds a little low at any rate, and that ten thousand is way to high. Is there any way you can give a little more info on the system. What kind of registers, piping, how many zones in each unit.

jackieo · Oct 9, 2008, 08:32 AM

Thx everyone for your answers. I'll try to be more detailed.
I'm not sure what "zones" are. We have 8 rads per floor. We are on one floor, others are on the other. The pipes are clearly not copper so I presume iron.
We have a thermostat upstairs to control our heat and they have one downstairs to control theirs.
In terms of holes in walls, I don't think that that will be an issue as we already have that going on. Square footage of each unit is approx. 1000. It's not a big home.

EPMiller · Oct 9, 2008, 10:50 AM

Originally Posted by jackieo

<snip>We have a thermostat upstairs to control our heat and they have one downstairs to control theirs.
In terms of holes in walls, i don't think that that will be an issue as we already have that going on. Square footage of each unit is approx. 1000. It's not a big home.

There are evidently 2 zones, so the plumbing is not too extensive. I have no idea how well the house is insulated, how good the windows and doors are, what the basement is like and so on so there is no way to really help with system design from here other than to say that it doesn't sound like an unrealistic job at all. Get several estimates and check their references. Make certain that you are comparing apples with apples on the type of furnace though. An 80% efficiency bare bones unit is not in the same league with a 92% (or more) efficiency variable firing rate condensing furnace with outdoor reset.

EPM

mygirlsdad77 · Oct 9, 2008, 03:17 PM

EPMiller is correct. High eff boiler such as wm ultras and the like are much more expensive and have much more intricate piping. Get more quotes and have them explain what they are quoting.
Replacing the two boilers with one is definitely do-able. You say the one person quoted $400 for extra piping, and another bid was for ten thousand. The latter was probably a bid for the whole job(boiler and materials included) Not completely unreasonable if you are going with a high efficiency boiler. I would be curious as to what the bid was from the first contractor, for the whole job.