3/4" to 1/2" to 3/4

AnthVale

I was wondering if I should I rebuild this section here so everything is 3/4" or is it ok like this?

The Backflow preventer is also corroded. I'm assuming I should replace this part and if so I was thinking I could get 3/4" if I needed to replace this section entirely. Then, I'd have to buy a new flow regulator.

Thanks in advance,

Anthony

Alan (California Radiant) Forbes

Not absolutely necessary, but yes, you can certainly clean it up. I'd like to see you get rid of the black pipe as it is prone to corrode and form a solid block of rust inside. The reduction and then increase in pipe size is no big deal. If you feel motivated, I would also pipe a bypass around the fill valve for easy purging and pressure control.

mattmia2

In your case since it looks like you have a lot to purge if you ever drain the system I would do the manual bypass that @Alan (California Radiant) Forbes shows in 3/4" and I would put a manual valve after all of it where it connects to the system so you can service the PRV without draining the system.

The 3/4" and manual bypass will let you get more velocity to purge the air out.

EBEBRATT-Ed

1/2" is plenty for a residential boiler and will save a few $$$

AnthVale

Thanks, everyone.

@Alan (California Radiant) Forbes I am draining the entire system in the coming weeks so any work like this will be done if it's recommended. So I can better understand the point of the bypass… Like @mattmia2 mentioned, is this strictly to get more velocity to purge the air out faster/easier? Where does pressure control come into play with this?

I'm new to this, is it more difficult to purge the system while the backflow/fill valve is inline? I'm guessing it hinders the flow?

Also, I have a good bit of Black Iron just above section too shown below. While I have the system drained, would it be a good idea to get this all to 3/4" copper?

My current plan is to plumb a new zone off the left side there and add a Purge Valve (this one here). Maybe I'll just buy three of those valves and re-build that entire area with 3/4" copper?

@mattmia2 Since there's a shutoff valve above the PRV already, are you saying to have one below and above so I can close both off and service the PRV/Back Flow Preventer?

I'm guessing I'm looking for something like in diagram B below?

Here is the system as a whole. Currently, the Back Room zone is not in place.

mattmia2

Diagram A is what you'd want. The isolation valves are just for service of the prv assembly. You may have existing valves that serve that function, I can't see all of the system from your pictures.

The bypass is just for purging, 1/2" is fine for the prv itself. Most systems do fine without the manual bypass but I can see where it would be easier than dealing with the fast fill lever on the prv(or auto fast fill) and more velocity might make purging easier depending on what your system is like and if you have a purge enough drain in the system to purge through without building up enough pressure to open the relief valve. You woudl watch the pressure gauge on the boiler and throttle the bypass valve to make sure it doesn't get to 30 psig and open the relief valve.

Black iron is fine in the hydronic heating side because there is no fresh oxygen in the system to continually corrode it like in a potable water system.

Is that pex the potable water system?

AnthVale

@mattmia2 As you can see in this diagram of my plumbing system, I don't think there is any valves before that section. Only one valve after it. Also, you can see I do have some purge valves on the individual zones.

I haven't done too much research on purging just yet so you did lose me a bit half-way through the second paragraph above. But, I'm guessing I will need to learn how to purge once I re-fill the system…but, it seems like plumbing in the manual bypass won't be hard to plumb in so perhaps I'll just add this to the system and learn how it all works after haha!

Regarding the PEX. Unfortunately, yes, my potable water is all 1/2" PEX. Thoughts on that?

The runs aren't overly long; I could prob replace it with 1/2" copper easily. I just bought this house (first time homebuyer) so I need to pick my battles here for now.

Although, water is of utmost importance to me considering I'm a transplant recipient and I am immunocompromised so I'm interested in your opinion on that.

Here is my entire system currently:

mattmia2

Pex is fine for potable water. I wanted to make sure that wasn't for heating because it looked like it probably wasn't the oxygen barrier version of pex that you need on a hydronic heating system.

If you shut off this valve before you work on the prv you shouldn't get enough air in the system that you will need to purge it.

I would add a valve here so that you don't have to shut off water to the rest of the house to work on the prv:

AnthVale

Great, thank you so much for all your help. So, would I be aiming for something like this:

mattmia2

We can cover how to purge the system later.

hot_rod

You don't want to pump at the expansion tank, move the tank to that lower tee before the circ pump.

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