Plumbing for boiler

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  #1  
Old 07-29-18, 09:31 AM
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Plumbing for boiler

Hello. I've gotten much closer to installing a new boiler, finally built a small extension so it will fit properly and removed the old boiler yesterday. Everyone has been very helpful since the beginning of this project (https://www.doityourself.com/forum/b...er-boiler.html).

Now that I am close to ordering and installing a new boiler (most likely going with Slant/Fin Liberty II with tankless coil) I am reviewing the existing plumbing. Most of the components are in good condition, some need to be replaced. I think the existing setup may be suitable but I'm not 100% sure. Below is a digram of the existing setup. I currently have a separate hot water heater so I understand the tankless coil will need to accounted for with new plumbing but is what I have already correct for just the boiler? Do I need to add/remove/reconfigure anything?

Thanks

 

Last edited by PJmax; 07-29-18 at 10:07 AM.
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Old 07-29-18, 11:02 AM
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D,
Starting with your boiler main supply line. You show a Flo control valve(FCV) going to each zone which you need with pumps but you show your expansion tank coming off of your Z2 FCV.

By putting it there you only have expansion protection when Z#2 calls for heat.

Your extrol must be located on the main supply before any of the zone supply's. Also is should not be hung off of a FCV but an air scoop of some kind, preferably a Spirtherm. This is very important in your case since you will have a tankless and the boiler will be running all year for hot water and there are times your heat will not be calling.

The only thing that opens those FC's are when the pump comes on so remove that extrol, install a Spirotherm and put the extrol on that between your boiler and before your zone 2 feed.

I'm sure you're going to hear about pumps being located on the supply side but if your pumps are already on the returns and it's too much work to relocate them it's not the end of the world with residential systems. They will work fine on either side.

If you do relocate them they must be installed after the extrol for them to make any difference since your tank is the point of no pressure change which is the purpose of the pump being on the supply side to increase pressure to the emitters and help with air removal but that's another story.

This is just a personal opinion but I find that air vents serve no purpose and if they fail can cause problems. If your vent fails and your pump comes on it can actually suck air into the system instead of releasing it. They have their purpose but if you have a simple series loop system where water is forced from supply to return through one pipe with your emitters as part of that loop, if your system is bled properly the air is forced out of your return line spigot and unless the system is opened up or you have another problem no more air should be able to get in.

http://www.supplyhouse.com/

If you go to this sight, click on heating and then Air eliminators you can see what is available and read the info on them.

Hope this helps a little.
 
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Old 07-29-18, 12:51 PM
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Thanks spott. So the expansion tank should be at the red dot on the image below? Attached to this - https://www.supplyhouse.com/Spirothe...aded-3559000-p


And the pumps have been in that location for many years, before I purchased this home, we've been using it that way for 5 years without issues.

https://www.doityourself.com/forum/a...1&d=1532893825
 
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Last edited by dtech80; 07-29-18 at 01:13 PM.
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Old 07-29-18, 01:23 PM
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So I'm thinking the system should look more like this.

https://www.doityourself.com/forum/a...1&d=1532895793
 
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Old 07-29-18, 03:45 PM
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Your revised sketch looks good to me - but wait until Spot blesses it.

But, I think your original drawing, as far as the flo-control valve, is OK. Flo-control valves typically have three connections. One connection goes to the downstream side of the valve. The other two connections are in common, both connected to the valve's inlet. Often, just one of the two inlet connections is used, but they are oriented 90-deg apart to accommodate different piping arrangements. But the remaining one can be used for whatever you want, including what your original sketch showed.
 
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Old 07-29-18, 04:40 PM
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D,
Yes, that is where you want your air scoop and extrol. You want to put your back flow preventer before the feed valve. That is in case something happens to your feed valve the BFP will prevent the boiler water from being syphoned into your potable water.

As Mike said, your FCV's are fine and do have those ports for different piping configurations but are not made for an extrol. The reason being it takes the pump to open them to allow the water to flow and if your stat wasn't calling for heat to that zone your extrol would be isolated from the system and most likely causing high pressure and your relief valve to let go at 30 PSI.

That Spirotherm is fine but I'm assuming it's going to be at least 1" depending how big your zones are. I only mention it because the one you showed is 3/4" and you're going to mount it horizontally for proper operation.
 
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Old 07-29-18, 05:33 PM
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The largest pipes in the system are 3/4". One zone is just one room, the other zone is only 5 small rooms (the single room is an extension), it's a small house. The setup is far from ideal, I'm sure, but I'm not ready to re-plumb the whole house.

Thanks for help spott and Mike Speed 30. I'm sure I'll be back with more questions soon enough.
 
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