Two Zone Hot Water Heating System
We have a typical one family brick Row House (18×45 with three floors: parlor, 2nd and 3rd with two rooms on each of the upper levels) with a hot water system. Is it better to keep the house as one zone or should we put the third floor on a separate zone? The third floor…
We have a typical one family brick Row House (18×45 with three floors: parlor, 2nd and 3rd with two rooms on each of the upper levels) with a hot water system. Is it better to keep the house as one zone or should we put the third floor on a separate zone? The third floor rooms will be used as a guest bedroom and the other a computer/office room and eventually a kids room. So the primary living area as of now will be the parlor and 2nd floor.
Also, do you feel that the big old cast iron radiators put out sufficient heat compared to a new baseboard cast iron radiator?
Thank you very much for all your help.
reno101, I think the additional motivation behind replacing old radiators is to reclaim part of space they take. Large radiator with cover can be reduced by 10 sf of floor. I assume you paid 150-400 $/sf for your house. So multiple these numbers and you see the point.
Thank you everyone for responding to our question.
Our boiler is very old and we will be replacing it next year. We just purchased the house this past fall and I’m not even sure of the size or manufacturer of the boiler. We are starting a renovation shortly and some walls will be open, so we’re trying to plan ahead if we need to run any pipes.
The reason why I inquired about the heat output of the old cast iron radiator is that a contractor we interviewed suggested replacing the old radiators because they don’t put out enough heat. I found that hard to believe because our house is very comfortable and anyone who went through a renovation would have installed current radiators. Sure you take aesthetics into consideration , but I believe keeping warm and low energy bills are more important.
When we purchase our new boiler we will definitely use a multi zone system. Thank you all again.
Capacity? But OP does not seem to be adding a zone, just re-zoning.
Denton said: “But one thing no one has asked is how many zones is your boiler capable of.”
I’m not sure there’s any reason to believe there is a numerical answer to that question.
What’s on your mind, Denton?
Agree with everyone, I would do at least one zone per floor. But one thing no one has asked is how many zones is your boiler capable of.
At 180Ëš boiler water temperature, cast iron baseboard radiators emit 550 BTUs per foot of convective heat. That’s the same output as typical copper fin-tube baseboard heaters.
http://www.governaleindustries.com/govboard.cfm
vs.
http://slantfin.com/documents/673.pdf
The most significant difference between the two is that cast iron baseboards also emit heat by radiant energy transfer, just like traditional radiators, the fin-tubes only by convective energy transfer.
This could be a long discussion, but I actually agree with cmu (it was bound to happen sooner or later).
Between the two, it’s a matter of aesthetic preference.
As for zoning, generally speaking, you’ll get greater efficiency by breaking the system down into smaller parts. But it can backfire on you and it raises the problem of how to efficiently fire a boiler with an output rated for the sum of those parts when only a small fraction of that energy is required as can be the case more than 50% of the time in a multi-zone system.
There are several ways to do this right (modulating boiler, buffer tank, outdoor reset, etc) and many ways to do it wrong (improper boiler size, flow rates, pipe sizes, water temperature, etc).
So, this could be an even longer discussion.
Last year, eman assisted us in a five zone (including passive Buderus hot water) system.
It has worked out well so I would encourage you to plumb as many zones as you possibly can. We ran pex to different floors, so copper may only be necessary out of walls to cast iron radiators.
The best feature of all, is the ability to route enough heat to the top floor, where previously it was never possible (even at great expense) to send enough heat to make up for the heat loss. That alone made it worthwile.
Also it has been more economical than oil-fired steam heat (it is now gas).
I rebuilt heating last summer and went with five zones (two per floor and one zone for basement). I am very happy with the setup. I do not see much advantage in having one zone beside saving on copper pipes.
Different radiators (a wrong word in itself, they’re convectors) will output the same heat level if they’re rated the same, it’s primarily aesthetics. Personally I like the big old radiators as they take less base room.
Possibly the heat distribution in a large space is better with baseboards (I have a semi-detached and the middle room is quite a bit colder because there’s no radiator there), but they may be more prone to restricted air movement, making the less heat efficient.
Assume you’re thinking of a third zone to save money by not heating the space when not used?