Variable Speed Pump 1/2" Zone

Reply

  #1  
Old 02-26-16, 11:47 AM
Member
Thread Starter
Join Date: Jul 2015
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
Variable Speed Pump 1/2" Zone

I currently have a 4 zone system in a 3 floor house cast iron baseboards throughout, 3 zones are 3/4" pipes throughout, one zone on the 1st floor is 1/2" piping. The boiler is a Galaxy GXH230 189,000btu non-condensing boiler powered by a Taco 0010-F1 pump. I'm thinking the pump is overkill for the 1/2" piped zone and a variable pump Viridian VT2218 maybe better handle that zone when it calls for heat alone. The weird behavior for that one 1/2" piped zone is the return water takes a while to heat up, but the boiler always overshoots the high limit by over 15F on it, never on the other 3/4" zones if they're open on a call for heat, then it just hits high as expected. So if the high is set to 180F on the AquaStat the 1/2" piped zone thermostat never satisfies the heat quickly like the other zones and the return hits 195F on the boiler temp gauge, all other zones usually satisfy heat a lot quicker and only on the coldest of days do they make the return water hit anywhere near 180F.

I'm stumped and wondering why a somewhat short zone piped 1/2" which heats half the sq. footage of living space as other zones behaves like this, and if a variable speed pump may benefit this setup when that zone calls for heat alone. Could the Taco 0010-F1 pump on the return side be too much for this zone and not flow or go through the piping properly?
 
Sponsored Links
  #2  
Old 02-26-16, 04:42 PM
Member
Join Date: Jul 2009
Location: Toronto
Posts: 1,174
Received 0 Votes on 0 Posts
simply because 1/2" pip has no bussiness being in a heating system.
What you say is over kill is actually not.
The reason it take time for the return to get hot is because your circulator is having a hard time overcoming the friction loses of the 1/2" pipe. The results is a low GPM flow rate.
 
  #3  
Old 02-26-16, 05:24 PM
Member
Thread Starter
Join Date: Jul 2015
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
Thank you for your response.

Would replacing the Taco 0010-F1 with a variable speed pump like the Viridian VT2218 perform better for the 1/2" piped zone or improve conditions when the 1/2" piped zone calls for heat alone?
 
  #4  
Old 02-26-16, 06:07 PM
Member
Join Date: Dec 2014
Location: USA
Posts: 37
Received 0 Votes on 0 Posts
I would suggest a visit to the Taco website and determine the cartridge pump that has more head capacity. I believe the 008 pump can handle a restrictive heat loop better and not be too expensive either. The route of the problem (is there one though?) is the 1/2" pipe size....too small!
 
  #5  
Old 02-28-16, 07:02 AM
Member
Join Date: Jul 2009
Location: Toronto
Posts: 1,174
Received 0 Votes on 0 Posts
the Taco 0010 is whats called a flat curve circulator, designed for high flow low head applications.
It has about 11 to 12 FOH available at low flow applications.

The VT2218 is a much steeper curve, and will give you 22 foh available at min flow.

How many feet of rad are on the 1/2" zone ?
Really the system should be piped primary / secondary as your small zone does not have the minimum flow rate to safely operate that boiler.

I would think the VT2218 would have noticeably better performance than the 0010 does, but I don't feel it's the proper solution for the problem.
 
  #6  
Old 02-28-16, 01:09 PM
Member
Thread Starter
Join Date: Jul 2015
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
The 1st floor 1/2" piped zone has 24ft of cast iron baseboard and 2 upright 4-1/2" Deep, 19" High, 17 1/2" Wide 10 section radiators. The 1st floor zone is about 125ft of piping.

So by primary/secondary I'd add a pump to the 1st floor zone?

The highest head ft needed from my calculations for the 3rd floor are 12.5, and this boiler is oversized by almost 2 from some other calculations if this factors into anything.
 

Last edited by GLeve; 02-28-16 at 01:52 PM. Reason: Add 1st floor zone pipe length
  #7  
Old 02-29-16, 12:31 PM
Member
Join Date: Apr 2014
Location: us
Posts: 672
Received 10 Votes on 10 Posts
GLeve appears to have two problems, sizing circulator for multi zone system and boiler water temperature control.

The new ECM technology high efficiency pumps with automatic delta T and auto adaptive flow control make sizing much easier. Auto adapt feature can adjust flow characteristics with a push button, a big help in multi zone systems. Why go with a legacy synchronous motor pump that cost a lot more to run and has fixed performance?

The newer electronic micro processor boiler temperate control/out-door-reset units have all kinds of features to optimize the boiler performance and make the building more comfortable. They have multiple settings i.e. boiler temp, delta T, max temp, room temp, type of heating elements, etc..

Many of the newer controls features are outlined in the Installation Manual for Tekmar 256, (which looks like rebranded as the Taco PC700).
Link: chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/http://tekmarcontrols.com/images/_literature/256_d_07.pdf

Many forum threads are about issues with legacy products that could be more effectively addressed with new generation products at the same or little added cost and improving performance.
 
  #8  
Old 02-29-16, 06:11 PM
Member
Thread Starter
Join Date: Jul 2015
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
I have an Aquasmart that I never hooked up sitting next to the boiler, it has the option for an outdoor reset module, which now makes more sense to setup. I'm hoping the Taco 0010 can be swapped out for a Taco Viridian variable that would be a better fit for the 4 zone system.
 
  #9  
Old 02-29-16, 06:23 PM
Member
Join Date: Jul 2009
Location: Toronto
Posts: 1,174
Received 0 Votes on 0 Posts
if I quesstomate right, I would say you have 12,000 BTU for the cast iron baseboard and say another 3,000 for the cast iron sectional. total 15,000 for the main floor. provided the second floor is not vasty bigger and has windows in it, then I would say another 15,000 btu up on the second, and maybe 25,000 for the third floor. 55,000 btu in total with an installed 190,000 btu boiler.
while 1.5 to 2 gpm isn't completely rediculas through 1/2" pipe, it does add lots of head to the whole equation.
Do we know if there is a boiler bypass, or is it primary secondary (I don't think so).
Clearly the boiler is oversized, and we need to understand the piping.
I would agree that the curve of the VT-2218 is going to improve things, perhaps use the 0010 in a primary loop around the boiler, or better yet feed into a buffer tank and use the VT to draw from the other side if it... try to limit short cycles.
 
  #10  
Old 02-29-16, 07:57 PM
Member
Thread Starter
Join Date: Jul 2015
Location: USA
Posts: 5
Received 0 Votes on 0 Posts
3rd floor has 25,500BTU radiation
2nd floor 26,500BTU radiation
1st floor 14,500BTU radiation
Basement 14,000BTU radiation
80,500btu of radiation

There's no boiler bypass or primary secondary.

The reason for the piping, this house was first renovated on the 2nd and 3rd floor a while back, the aluminum fin radiators were swapped out for cast iron, but the piping stayed 3/4". When the 1st floor was upgraded from aluminum fin to cast iron years later, the crew that did the job reduced the piping in some sections when they installed cast iron radiators from 3/4" to 1/2", especially the connections to the radiators, they're all 1/2", I KNOW DUMB MOVE, when questioned about it they said it wouldn't be a problem.
 
  #11  
Old 02-29-16, 08:51 PM
Member
Join Date: Apr 2014
Location: us
Posts: 672
Received 10 Votes on 10 Posts
The Tekmar out door reset units are aquastats but with far more features and come complete. Control unit and 2 sensors. One for outside wall and the other for boiler aquastat well. It has 8 connections ...2 each for sensors, 2 for 24 vac and 2 are for contacts that close to start burner.

The Taco PC700 comes with a special plug that fits their -EXP model $100+ controls. Since most systems already have something handling those functions the EXP unit is an unnecessary expense.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: