expanding the possibilities of my boiler


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Old 10-13-09, 06:14 PM
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expanding the possibilities of my boiler

Wondering where I could find information for expanding my boiler system. I am interested in using the boiler for domestic hot water, and also expansion for a driveway ice/snow melt system. Any good resources out there?
 
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Old 10-13-09, 07:22 PM
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Without a doubt, John Siegenthaler's book "Modern Hydronics" would have your answers... and much more... but it's a pricey volume, around $150 or so. Check your local library.

Most of the I&O manuals for boilers have numerous piping diagrams in them, and much can be learned by studying them. Ditto for the information by Tekmar and Taco... Bell & Gossett has information on their website that is good reading too.

Adding an indirect water heater is for the most part the same as adding another heating zone, but snow melting applications are more complicated, mostly requiring a heat exchanger, with the snow melting loop being isolated from the boiler. Anti-freeze is mandatory, as is protection for the boiler to prevent condensation problems.
 
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Old 10-14-09, 06:44 AM
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Snow-melt, like radiant heating, is not hard to get right, but it is very, very painful to get wrong. Even if you do it right, snow-melt is quite expensive to run.

There's a recent thread here where someone installed some tubing under a driveway in hopes of doing snow-melt, apparently with little thought as to design and operation. There are some issues in the response that cover a few of the considerations.

Indirect is easy, as Trooper says.

Another easy way to 'expand the possibilities' of your boiler is to add an outdoor reset and DHW control to the existing boiler. That will not only improve fuel savings, but improve comfort as well. A major manufacturer of boiler controls, including snowmelt, etc. is tekmar. tekmar Control Systems Home Page
 
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Old 10-15-09, 08:36 PM
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so, what exactly does the outdoor reset, and the DHW switch do? Secondly, why is an indirect water heater system much more expensive than a conventional water heater? With the indirect system, there are much fewer parts??.... Finally, I am an audio/video guy, and an automation junkie as well. Are there any thermostats out there that are remote controlled via IR? I have found some remote controlled thermostats, but they are all controlled via RF....
 
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Old 10-16-09, 04:44 AM
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Why the preference for IR over RF?
 
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Old 10-16-09, 05:04 AM
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Read about outdoor reset here:

http://www.taco-hvac.com/uploads/FileLibrary/OM01.pdf

and here:

tekmar Essays

it is more efficient, and more comfortable.

Indirect is about the most efficient way to make hot water. Few moving parts (circulator, aquastat).

If you like automation and widgets, check out the tekmar controls. You can set up your house to be accessed from the internet.

Also check out the WEL. Web Energy Logger
 
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Old 10-17-09, 06:11 PM
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thanks for this information. I found a thermostat that someone else recommended to me in another thread on this site. I ordered the venstar... I believe it is the t-1700 or something to that effect.

drooplug Why the preference for IR over RF?
The reason for this being is that with RF, it is much more difficult and expensive to integrate into a control system. where as IR, IP, or RS232, can be easily integrated into various control systems. But for IP, and 232, a true automation controller is required, which is very expensive. With IR control, it can be connected to a rather simple remote control system, with an RF, to IR gateway in which remotes interface with, still able to utilize IR, but when the gateway is used, the remotes can be used anywhere.
 

Last edited by NJT; 10-17-09 at 06:28 PM.
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Old 10-17-09, 06:34 PM
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Yeah, automation is nice, but just wait till the ham radio dude next door fires up that kilowatt and starts sending morse code... man, talk about a light show! All the X10 devices going nutz, heating system cycling on and off, garage doors opening and closing... fun stuff!

Someone recently posted something about a thermostat that was HA enabled... it wasn't the one you mentioned... but for the life of me, I can't remember what it was. I think I moved his post over to the 'thermostat controls' forum, might look there.

why is an indirect water heater system much more expensive than a conventional water heater?
They are certainly much more robust that any of the off the shelf units for electric and gas! And a good many of them are stainless steel tanks, probably the last water heater you will ever buy.
 
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Old 10-18-09, 01:39 PM
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Originally Posted by NJ Trooper View Post
Someone recently posted something about a thermostat that was HA enabled... it wasn't the one you mentioned... but for the life of me, I can't remember what it was. I think I moved his post over to the 'thermostat controls' forum, might look there.



They are certainly much more robust that any of the off the shelf units for electric and gas! And a good many of them are stainless steel tanks, probably the last water heater you will ever buy.
First of all, there are a lot of thermostats that can be controlled by a third party device. There are a few other ones that I would prefer, but dont feel like spending $1500+ for the automation controller to run it at this time. Secondly, I hope that you are right in saying that it would be the last water heater I would buy. But since its indirectly heated and will probably heat much faster, how would a guy go about sizing something like that? Currently I have a 40 gallon natural gas water heater.
 
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Old 10-18-09, 01:55 PM
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I just went from a 50 gallon direct fired to a 35 gal indirect. It's just me and my wife right now and we haven't had any trouble. The typical routine is that I shower first and then about 15 minutes after my water stops running, she gets in and takes hers. I have gone down into the basement while she is in the shower to observe the boiler and it will satisfy the temp of the water tank just fine. I imagine that if the shower was the only thing using hot water, I would never run out of it. Not sure how things would go with two showers running.
 
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Old 10-18-09, 03:50 PM
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well, that sounds pretty good. I am in a similiar situation, only have one shower, and am simply after a constant supply of hot water. Ideally, I would like to be able to run multiple things and not run out of water -- shower, and dishwasher, etc. However, I did find a 120 gallon unit, but talk about expensive! That was roughly $2500. May I ask, roughly how much was your 35 gallon unit?
 
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Old 10-18-09, 03:54 PM
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I have no idea. pexsupply.com is quoting about $880 for a 35 gal burnham alliance.
 
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Old 10-18-09, 04:09 PM
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I think that the 120 is WAY overkill ... I've seen 'sizing guides' on some of the manufacturers websites. I would think that a 40 gall unit would suit your purposes just fine, but that's a WAG. YMMV.
 
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Old 10-18-09, 04:21 PM
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A 120-gal heater might be appropriate for an apartment house or motel?

Probably 95% of self-fired water heaters are 40 gal. Some have quicker recovery times than others. (I'm aware that a separate, fired water heater isn't what you're talking about here.)

Do you burn gas or oil?

It seems like this thread is wandering all over the place - snow melt, domestic water heating, outdoor set-back, etc. Probably best to treat each topic as a separate thread?
 
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Old 10-18-09, 06:08 PM
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35-45 gallon indirect would be fine. Check out the Triangle Tube Smart Series (tank in tank design), the HT Products SuperStor (coil heat exchanger design), among others.
 
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Old 10-18-09, 07:01 PM
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Originally Posted by NJ Trooper View Post
I think that the 120 is WAY overkill ... I've seen 'sizing guides' on some of the manufacturers websites. I would think that a 40 gall unit would suit your purposes just fine, but that's a WAG. YMMV.
I simply think that having that large of a water heater would be really cool.... You could never run it out of hot water!! But I will have to look at some manufacturer websites and see what I can find for sizing specs. Finally, the boiler that I am using and intend on connecting this unit to burns natural gas.
 
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Old 10-18-09, 07:56 PM
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Actually, you probably would run out.

For a 120 gallon unit, you need a boiler output of around 275k BTU/hr to get rated performance.

Your cga-4 has a DOE output of 88k BTU/hr. That's 3x smaller. You're pulling a freight car with a Chevette.

Consider....

120 gallon indirect has a usable capacity of 95 gallons. At 2.5 gpm flow of hot water, you have 38 minutes of hot water.

To recover the tank, you need to raise 1000 pounds of water about 90 degrees. That requires 90,000 BTUs. Assuming your boiler actually puts out 88,000 BTU/hr, that's a bit over an hour to recover the tank. Maybe a bit less since it won't be a full 90F rise.

If you planned your usage times and durations carefully, maybe you could do this. e.g., shower before leaving the house, and with a DHW priority control, it won't matter that the house goes without heat for an hour while the tank recovers.

The larger tank also has higher standby losses.

If it was really efficient to do it this way, it would be common. It ain't.

(But a 120 does make a nice solar domestic hot water tank, like the one in my basement....)
 
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Old 10-18-09, 07:57 PM
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Problem is though, you probably will find that the boiler can't keep up with it... say you run a load of hot water washing all the cars in the neighborhood... by the time that big old tank calls the boiler to heat it up, it's full of cool water... then yer itty bitty boiler gonna be humpin' trying to get all that water hot... and it will cost ya a fortune to run, let alone install. You would need something like a 300K BTU boiler to get any decent recovery time outta a big ole tank like that.
 
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Old 10-18-09, 08:11 PM
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Originally Posted by xiphias View Post
Actually, you probably would run out.

For a 120 gallon unit, you need a boiler output of around 275k BTU/hr to get rated performance.

Your cga-4 has a DOE output of 88k BTU/hr. That's 3x smaller. You're pulling a freight car with a Chevette.
Yes, you all do prove an excellent point, but the cga4 is actually rated at 105k btu. but yes, I thought it would just be a cool idea, but yes, I thought it was probably not possible to do. I was looking at the burnham alliance units, I was looking closely at the 35 gallon, or the 50 gallon unit. Unfortunately, the 50 gallon unit requires 110k btu from the boiler, I am not sure how hard it would be on the boiler if I were 5k btu short.
 

Last edited by NJT; 10-18-09 at 09:06 PM.
 

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