System Setup Advice Needed


  #41  
Old 02-13-15, 04:18 PM
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There's no need for the Spirovent on the water heater loop, nor do you need an expensive DP pump. Use a regular old garden variety 007. There's nothing to be gained using a DP pump there.

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  #42  
Old 02-13-15, 04:22 PM
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There's no need for a DT pump on a radiant loop with a mixing valve. Use a regular old 007.

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  #43  
Old 02-13-15, 04:25 PM
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The radiant mixing valve won't work well the way you've got it placed. There will be very little flow through the boiler when the radiant zone calls...

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Old 02-13-15, 04:47 PM
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No matter what you end up with I most definitely would recommend that you stay with primary/secondary on the main heating loop. This would more easily facilitate your goal of constant circulation.

I don't like the idea of using an expensive electronic gadget to do boiler protection. Passive thermostatic devices would be my preference.

193B1701 - Danfoss 193B1701 - ESBE Series 1-1/4" 3-Way Thermic Valve (Body Only)

193B1704 - Danfoss 193B1704 - ESBE Series Thermostatic Element, 140F Opening Temperature

It seems that your desire is to do a fairly large 'start over' when the wx warms up...

I didn't go back and re-read, and don't remember... did you tell us that you have cast iron standing radiators in the home? and that ALL the piping to them is large diameter steel?
 
  #45  
Old 02-13-15, 04:55 PM
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For the moment, pretend you don't have the radiant subsystem, or the indirect. Take a study of this diagram...

 
  #46  
Old 02-13-15, 05:07 PM
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Thanks for the advice as usual. I will go back to my "professionals".

The DWH spirovent was suggested by the manufacturer. Their reasoning was that the boiler will fire during the non-heating season. I agree this is not really needed. With the main system air elimination this should not really be a problem. I have no air elimination now.

I also see you point about ECM's on the radiant and DHW loops. These can greatly reduce energy usage but may not have a payback in my lifetime!

Yes - my system is a typical converted gravity - two sets of 2" mains leading to large feeds to all cast iron radiators. Virtually all pipes are 1 inch to radiators.
 
  #47  
Old 02-13-15, 05:11 PM
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You have no room in there for a decent size buffer tank, is that correct?
 
  #48  
Old 02-13-15, 05:12 PM
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These can greatly reduce energy usage but may not have a payback in my lifetime!
Especially if they happen to crap out on ya... you can buy a LOT of 007s for the price of one of them!
 
  #49  
Old 02-13-15, 05:20 PM
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I do not believe there is physical space for a buffer tank. Is this related to the radiant zone? The "professionals" do not really address any modifications to this small zone. As noted in the drawing it is just kind of ignored.
 
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Old 02-13-15, 05:25 PM
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Is this related to the radiant zone?
No, not really, more to the idea of constant circulation.

That drawing was the ideas of the contractors you had in?

If they recommended doing away with the P/S piping on the main loop, I wouldn't put too much stock in their advice.
 
  #51  
Old 02-13-15, 05:33 PM
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There has not been a consistent theme. One contractor recommended P/S stay along with my existing controls but no new bypass system - another did away with P/S and added controls. The drawing is a compilation of thoughts. I am meeting one more person next week. I will get back after my discussion with them.

As you questioned, this is a significant (not cheap) do over and I want to get it right. I really appreciate your time, experience and analysis.

As usual you have given me more things to consider and research. To be continued...
 
  #52  
Old 02-13-15, 07:14 PM
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SJ Trooper

I think I actually understand your point about P/S on the main zone. Note that I have also added a boiler pump.

Please comment on the attached arrangement.

This will be the last submission to you for now. I will likely have "professionals" implement this but I want to understand what is being installed. Based just on two contractor visits it is clear that everyone with a truck/card does not fully understand what I am setting up. The sketch still includes a DWH Spirovent and the electronic controls. I will deal with that later. I just want your overall comments.

Thanks
 
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  #53  
Old 02-13-15, 07:20 PM
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Of course I meant NJ Trooper!!

No offense intended.
 
  #54  
Old 02-13-15, 09:02 PM
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One thing I forgot to mention is that the drawing should show a 4 way valve. This prevents a condition when a fully closed valve allows no return to the boiler.

Thanks for comments
 
  #55  
Old 02-18-15, 10:06 AM
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NJ Trooper

I met with yet another HVAC professional today. P/S stays as you recommended. I am attaching a sketch that represents the revised system.

In accordance with your previous comments - I have added P/S, removed the DWH Spirovent and stayed with Taco 007 pumps (except for the main zone, the Taco VT2218 ECM is already in place). I continue with the electrically actuated mixing and Taco 403 controller. I have also added a thermic bypass and additional boiler protection.

My intent is to independently keep my relays to on/off control the small radiant zone. At 10 deltaT it only requires about 1 gpm, it has its own existing motorized mixing valve and would not be part of the DWH priority. With a 140 degree boiler minimum it will essentially always get adequate supply without affecting the overall operation (at least my assumption).

It will be zero degrees tomorrow night! This work will not be done in the next week for sure. I will likely get a plumber to make the piping changes but do the wiring and programming myself. I am an EE and and very comfortable with the electrical part but plead ignorance on hydronics. It also may explain my desire to tinker for best results (ECM pumps included).

I appreciate your experience and piping comments.
 
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  #56  
Old 02-18-15, 10:24 AM
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What's the purpose of the pipe in parallel with the bypass pipe to the ESBE valve?

Why is there " NO FC " on the boiler pump? Without a flow check in that pump when the indirect pump runs it will pull from the system... I believe you need FC in BOTH those pumps.

Why is there a flow check on the radiant floor mixer?

I think I understand what you're trying to accomplish with the mixing valve on the main zone, but I'm not sure that you'll get acceptable results ... You may end up with boiler short cycling issues.
 
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Old 02-18-15, 10:41 AM
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My concern is that a condition where the return water is less than 140 degrees the ESBE valve will be closed with no where for the return to flow. It is also shown in the Danfoss literature.

I show an FC for the radiant mixer only because there is an existing Taco FC in the supply piping to the mixer. Like much else existing it may be incorrect. Upon your recommendation this can be instead included in the pump. My belief was that it would be OK for the mixer to pull directly from the boiler. As stated earlier it only has about 1 gpm requirement.

Why short cycling?
 

Last edited by NJT; 02-18-15 at 04:26 PM.
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Old 02-18-15, 10:44 AM
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I said indirect but I meant the mixer. The indirect will have its own flow check.
 
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Old 02-18-15, 11:02 AM
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I think I understand your comment now. I should also add a FC to the supply of the system pump. The mixer supply, and its supply FC, can then be rerouted to the intake side of the system pump. With this the indirect will be prevented from pulling from the system.

Sound OK?
 
  #60  
Old 02-18-15, 04:27 PM
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My concern is that a condition where the return water is less than 140 degrees the ESBE valve will be closed with no where for the return to flow. It is also shown in the Danfoss literature.
Your concern is not valid if you have the P/S close tee setup.

If you look at the Danfoss lit, you will see that this is not a P/S system with CSTs.

The pipe between your CSTs takes care of that concern.

Adding that pipe will 'short out' the flow to the main system when the ESBE does open.

I said indirect but I meant the mixer.
I edited your message...

The mixer supply, and its supply FC, can then be rerouted to the intake side of the system pump.
No, I think you want to leave that where it is.
 
  #61  
Old 02-18-15, 04:40 PM
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Why short cycling?
For the same reason that it will probably short cycle when only the radiant floor is calling for heat.

You've got xxx BTUH output from the boiler and you are only pulling a small amount of that off for the radiant floor.

The boiler will be burning rubber to get to the next stoplight, the radiant floor will crawl like a turtle.

So you've got big BTUs coming out, and only drawing off say 5-6 thousand. Boiler will hit it's setpoint quickly and shut off.

Same sorta thing with the big loop. Even though it has the POTENTIAL for higher output, when you reset the temp of the loop to something much lower, it will only be pulling minimal BTU from the system and the boiler will heat quickly, and the burner will shut down.

This is the reason I had mentioned buffer tank earlier.

Think of the buffer tank as a 'battery' full of BTUs. Your big ole boiler can recharge that 'battery' when it needs to, and the zones can 'discharge' it by drawing from it slowly.

The boiler cycles will be longer to recharge the tank, but further apart so the 'net' is roughly the same.

You would need a fairly large buffer, and I think you said you didn't have room for it anyway.

I see you are thinking of using the Viridian on the main loop... again though, I really don't think that's necessary with the mixing valve. You want to FLOW that big loop and let the mixing valve control the temperature. You don't want the pump slowing the flow to try and equalize DT because this will lead to imbalances among the radiators if it slows the flow too much.

Still thinking...

Maybe I'll scribble on your drawing a little bit.
 
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Old 02-18-15, 04:50 PM
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On your drawing it says about the radiant pump " No elec conn to boiler "

Does that mean that you intend the radiant floor to 'ride piggy back' on heat calls from the main floor and use whatever hot water comes it's way? In other words, it won't be allowed to fire the boiler if it calls all by itself?
 
  #63  
Old 02-18-15, 05:09 PM
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Truly excited to see what you recommend!

I had planned to control the 1 GPM mixer/radiant independently as an on/off device pulled directly from the boiler. It would not be controlled by the Tekmar controller. It is only about 4% of the boiler net capacity, which is already higher than needed to heat the home. It will have whatever it needs, especially as a low temp device. Essentially it would be parasitic to the system. No boiler calls allowed.

I see your point about the bypass line I show. It is not needed with CSTs. I will also rethink the Viridian. It can also be run at fixed speed but still at less than half the energy usage. (I know - no payback - but as stated I like to experiment).

I can restate that there is no physical space for a buffer tank. I am actually trying to make space for a relocated expansion tank. It is now located in an inaccessible corner behind the boiler.
 
  #64  
Old 02-19-15, 05:40 PM
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It's not going to be much different that what you had drawn...

This is not complete... I'm still undecided on a few things;

Whether or not the flow check is needed on the radiant zone, I don't think it is.

The location of the radiant zone, before or after the ESBE. If the radiant zone doesn't call the boiler, just a parasite, it might not matter at all. It either gets heat or doesn't.

Whether or not the mixing valve and constant circ on the main zone is a good idea without a buffer tank 'battery'.

Anyway, here is what I've got so far, you see not many changes at this point. I only moved the water heater to the side to clear up the diagram a bit. It's still physically connected to the same place.

I did change the water feed and valves at the expansion tank a little, note that there is a drain on the tank side of the isolation valve for easier service of the tank.




Click here for full size image
 
  #65  
Old 02-19-15, 09:45 PM
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NJ Trooper

I cannot thank you enough for taking the time to review this and previous setups. I feel I have come close (not quite) to your general approval that at least what I propose is not "off the wall".

I take your comments very seriously and have made many changes since my original post back in January. This has been an education.
 
 

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