Help: Call for heat by indirect HW heater = passive heating throughout home

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Old 10-29-08, 11:26 AM
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Help: Call for heat by indirect HW heater = passive heating throughout home

Hi all,

I recently did what I thought to be a 1-to-1 swap of a Smith series 8 boiler in my home. The boiler heats a three zone hot-water baseboard system, with a fourth circulator for an indirect hot water heater (Boilermate). I've tried to sketch up the sytem, hopefully it will come through:


http://i458.photobucket.com/albums/q...tingsystem.jpg

The new unit heats the home wonderfully, just in time for winter. But there's one catch: when the hot water zone calls for heat, as intended the boiler fires, and only the HW zone circulates, until the thermostat is satisfied on the indirect tank. BUT, I'm getting heat from my upstairs baseboards, even though those circulators are not running. Sure, heat rises and temperature differentials cause circulation -- I know that it is some type of passive flow, because if I close the shutoffs on the zones (not shown in the diagram), right above the circulators, and fire the HW zone, I get no sneaky escaping heat. When those shutoff valves are opened, and there's a call for the HW zone to run, I get about a 6 degree temperature rise in my house.

I've realized that this system is not plumbed ideally - but what is strange is that this didn't happen on the older boiler - I didn't have this problem before, and I don't know why its happening now. I did replace the swing-check valves and I replaced some iron pipe with copper, but that's about it.

With that info to start, does anyone have any ideas how to solve this, without ripping apart the system and doing zone valves? Maybe I need to be asked the right questions or look at this another way...I'm really stumped.

Thanks!
 
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Old 10-30-08, 09:05 AM
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Spring checks are generally better at preventing gravity or ghost flow than swing checks.
 
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Old 10-30-08, 09:54 AM
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You could try adding flow checks for the three zones after the pumps before the return.
 
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Old 10-30-08, 12:58 PM
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Originally Posted by rupert326 View Post
You could try adding flow checks for the three zones after the pumps before the return.
Originally Posted by xiphias View Post
Spring checks are generally better at preventing gravity or ghost flow than swing checks.
Part cost aside, is one better a better solution than the other? The manifold of pipes leaving the supply-end of the boiler heats up a lot, where the swing-checks are now.

Does it make a diff if they're installed horizontally or vertically?

Thanks so far!
 
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Old 10-30-08, 01:26 PM
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Swing checks and spring checks are both in the general family of flow checks. (At least as I define them, which may technically be incorrect. ) They both "check" the flow, but the manner in which they do it is different. The spring type flow-checks are typically used to prevent the heat migration you're experiencing.

These work well:

http://www.taco-hvac.com/uploads/Fil...ry/100-7.5.pdf
 
 

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