View Full Version : Boiler questions for new home construction
11-19-2009, 03:00 PM
Looking for some help. In the process of building a new home. Basement, main floor, second floor and then a loft with a bedroom and playroom area. Relatively large size home. (I have a lot of kids, in laws over a lot etc)
Planning on using a boiler system for heating and domestic hot water, as well as radiant heat in the basement. Any thoughts on the following proposal?
Lennox hot water fan coils model CBWMV (2 units)
Lennox 13 SEER air conditioners model XC13 (2 units)
Nortec Steam humidifier
Pleated Air filters (2 units)
Programmable thermostats (2 units)
Heat source will be 2 Weil-McLain CGi-6 boilers. We are also doing a backyard pool and considering using the boiler(s) to heat the pool. (I have looked around and noted that the efficiency rating for these units is not great. I could "upgrade" to an Ultra condensing boiler for an upcharge of $).
11-19-2009, 03:20 PM
Why humidifiers? Not building a tight house? Low humidity is caused by infiltration. Build it right and you should have excess humidity, not need 2 humidifiers!
Yes, the CGi is not that efficient. I had to remove your upcharge since rules prohibit pricing but might not be a bad idea to go to a mod-con. Also 13 SEER is rather low by today's standards but if you are in an area with limited cooling needs, could be OK.
Only other thought is using heat pumps for mild weather so you don't have to fire up the radiant and wait for the floors to warm up.
11-19-2009, 07:46 PM
Why are you planning on using a 84% boiler to provide hot water to an air handler? Why not a high efficient furnace instead? Or why not use a modulating high efficient condensing boiler with outdoor reset if the hot water air handlers are a must.
The mod/con boiler will add cost, but if you heat a pool off it/them also, the fuel savings will be substantial.
If your borrowing to build, have your contractor run a cost analysis to show the savings on your energy bills. I think you'll be surprised to find out that adding the costs of upgrading the equipment verses the additional monthly payment on the mortgage to be a wash and if everything is chosen carefully you could actually see a savings per month after it's all built.
11-19-2009, 07:56 PM
Get the Ultra.
It will work better for your radiant heat.
11-19-2009, 09:57 PM
there are many reasons to go with a mod con over a traditional cast iron mid 80's efficiency boiler. a properly installed and controlled mod con will give you better energy efficiency, and a more comfortable home. the difference in cost amortized over the life of you mortgage is nothing. the added energy saving and comfort will be well worth it.
11-19-2009, 10:20 PM
I agree with all above, get the Ultra, or some Modulating Condensing Boiler.
I also agree it might be better to use high efficiency furnaces, and then just use the boiler for the radiant, domestic hot water and pool heat.
Are you burning natural gas? I ask because if you are burning propane, I strongly suggest a heat pump to heat the pool over using a boiler. If you are burning natural gas, the price of the fuel would still probably be cheaper to heat the pool with a heat pump, but maybe not so much that it warrants another piece of equipment, assuming you are getting a boiler for other needs. Further, if you are burning propane, it is advisable to use heat pumps with propane furnace back-up. This will more than likely be the cheapest to run, but your install cost will increase quite a bit.
Also, this better be one HUGE house to need two boliers. It's alot more plumbing - waste of money. Go with one boiler sized for the whole load. You do not have a hospital or school where you need redundant capacity.
You may notice I keep saying "probably" and "more than likely" - this is because these statements depend on your local fuel cost (including electric). Not only now, but in teh future as well. Everything I said is true for my area, now.
11-19-2009, 11:13 PM
modulating condensing is pretty much the only way you should be thinking or else youare just going backwards in building a house. i presume will be yours for a long while and to heat a pool with only electricity as in a heat pump or condensing boiler in my opinion is also going backwards i would at least rough in for solar panels 4 to start and also make pretty much free hot water inthe summer and heat your pool it works very well i have seen several and installed several and even the best boilers cost 200.00 a month to keep a pool at 80 f
11-20-2009, 09:27 AM
Thanx for all the replies. The house is actually going to be pretty big between the basement, main floor, second floor and third floor loft area.
In terms of geographical location, I am in Toronto. The winters do get pretty cold and the summers can get pretty hot and humid. One of my daughters has some very severe dry skin issues and we have found that over the course of a long winter with the furnace on for months at a time, the house gets extremely dry and that is why we are looking at the steam humidifier unit.
I did a bunch of reading on the boiler that was initially suggested by the contractor which is what led me to believe it would not really be an appropriate unit. I then came across the Ultra condensing boiler but there was quite a significant upcharge. What is the modulating condensing?
Thanx again for all the very helpful and useful comments.
11-20-2009, 10:36 AM
The modulating part means it will vary its output based on the needs at any given time. The condensing part means it is a high efficient unit that utilizes latent heat from the flue gases as well as the heat from combustion.
11-20-2009, 02:11 PM
You keep saying pretty darn big - how many square feet.
To some of us - pretty big means 300,000 square feet! :angel:
11-20-2009, 02:24 PM
1st floor, second floor and 3rd floor loft area apx. 6,800 sq. ft.
11-20-2009, 02:41 PM
Lochinvar Knight KB-285. :yes:
But don't take my word for it - make sure a good heat loss calc is done.
11-20-2009, 04:02 PM
Just finish a similar project using NTI Trinity Combi. 4200 sq ft works great and provides adequate water for 3 showers and hot water for 2 at the same time. This can also supply the radiant heat. Address the building envelope first and reduce your HVAC needs. No mention of ventilation... HRV? Investing in better equipment upfront will pay for itself over the years. You can save money with less efficient equipment now but you will pay for it every time it runs in higher utility bills. Your contractor should be able to do a payback analysis on the different systems to help you decide.
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