Looking to upgrade 50 yr old 1/2” trunk+branch plumbing

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yNotry

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Hi all,

I’m planning to upgrade my 50 year old 1/2” trunk+branch copper plumbing so my 90 yr old Dad can live downstairs. I’ve been doing a bunch of research and reading from this forum. Lots of great helpful questions, info and feedback. I’d appreciate feedback to confirm and improve what I’ve got so far. Basically I’m thinking of replacing the 1/2” copper trunk with 1” PEX from the well tank to new manifolds with 1/2" PEX runs of 10 to 30 ft to six groups (2 kitchen, 3 bath, 2 washer) per attached sketch. The house is one story so runs will be through the ceiling of basement then up or down. My understanding and assumptions thus far are:

1. Bend PEX instead of using elbows. Use long elbows instead of short. In my case around the well tank and cold manifold.

2. Orient tees to either equalize or give preference/reduce pressure due to added equivalent length.
In my case and per sketch (except for Kitchen, Bath, Washer Groups):
a. Orient first trunk tee straight 1” with 1/2" to side for Hose Bib run
b. Orient Hose Bib 1/2” tee straight for longer Front Bib run, off to side for shorter Back Bib run
c. Orient ByPass 1” tees straight for House Filters, side for ByPass
d. Orient Cold Water trunk tee straight 1” to HW Heater with 1” to side to Cold Water manifold
e. Orient RO Filter tee straight 1” to Cold Water manifold with 1/2” to side for RO Filter run
f. Orient Kitchen Group run DW tee straight to Sink with side to DW (not shown in sketch)
g. Orient Bath Group run Sink tee straight to Tub+Shower with side to Sink and then Toilet tee straight to Sink with side to Toilet (not shown in sketch)
h. Orient Washer Group run 1/2” tee straight to Upstair Washer (longer run) with side to Downstair Washer (not shown in sketch)

3. Size tees+side runs to give preference to a fixture ie Tub+Showers over Sinks and Sinks over Toilets or DW’s. Does this mean 3/8” side to Sink off 1/2” run to Tub+Shower OR 3/8” side to Toilet off 1/2” run to Sink? And 3/8” side to DW off 1/2" run to Kitchen Sink?
4. Size H+C manifolds and trunks 1”, up to 3/4” HW Heater inlet and 1” from 3/4” outlet to HW manifold.
5. Each Manifold group is within 6 WSFU limit for runs less than 40 ft and House Total of 22.4 is within 1” source total of 32 per ICC and state codes.
6. Change 40/60 psi pump switch to 50/70 with CSV set at 60psi. Should be no issue with pipes et al. Any issue with a 1/2 hp 10 gpm submersible Gould pump 100 ft down in well 75 ft from house?
7. Change well tank (and draw down) from 20 to 36 gal (from 5 to 10 gal draw) if/when tank goes to increase (double?) pump life. Most use is small (toilet, hands, dishes, no DW) with high use (shower, wash) only 3-4 times a week. House electricity monitor shows pump on 15x on low use days for total of 75 gal (5 gal draw x 15), 30x on high use days for total of 150 gal. With 2.5 gpm showers, this would mean going from average (half tank) 1 to 2 min or worst case (full tank) 2 to 4 minute wait time for CSV constant 60 psi. Big difference tho will be wait time ‘low’ will be better at 50 psi than current 40. Do I have this right?

All feedback and heckles from the peanut gallery welcome.

Plumbing Design - Sketch.jpg
 

jadnashua

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How far to the various use points, and is there a more central location where you could put the manifold so you don't have lots of long 1/2" runs versus one longer 1" one to it?

While you're running piping, consider installing a hot water return so you can add a recirculation system. It's easier to do it at one time, but you don't have to use it unless you find you don't like the time it takes to get hot where you want. Keep in mind that PEX can't handle exposure to UV, so if it might see that in the runs, it must be protected...most give you up to 30-days to protect it during the buildout. Code wants all of the hot lines to be insulated, and making them shorter, with one larger one feeding it will make that cheaper and easier, too.

With insulated lines and maybe a timer so it doesn't run when not needed, the wasted water, sewer charges, and energy use can end up less with a recirculation system versus without, and, it effectively makes your WH larger. Think of it this way...you want hot water and it takes 90-seconds to get there first time of the day. Say the faucet uses 2-gallons per minute...that's 3-gallons of hot water you paid to heat that you didn't get to use for its intended purpose. With the lines precharged with hot, you have hot there almost instantly when you open the tap, and the whole tank is full of hot that wasn't diluted with the incoming cold water running the tap without. Depending on where you live, water can be precious.

I would run a larger pipe to your hose bibs...the ID of PEX is going to generate some friction and pressure loss when you ask it to have a high flow. Expansion fittings with PEX-A will have less restrictions in it, and it's more flexible and can handle a tighter bend than types -b or -c. It's also the only one that can be restored if you kink it. The other types require you cut out the kink and substitute a fitting...type -a, with a heat gun, can be restored without.
 

yNotry

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How far to the various use points, and is there a more central location where you could put the manifold so you don't have lots of long 1/2" runs versus one longer 1" one to it?
Thanks jadNashua for all the suggestions and feedback - much appreciated. The longest run is to the front bib at 35ft and shortest back bib at 5 ft. The others are all 25 ft or less - upstair kitchen 25, washer 20, bath 15, master 10, downstair washer 20, kitchen 15, bath 15. The manifold is about as centrally located as can be. I’ve thought about moving 7 ft to other side of room which would shorten half the groups while lengthening other half and reducing front bib 5 ft. Would be a bit more work to move stuff. Is it worth it for not much net difference?

While you're running piping, consider installing a hot water return so you can add a recirculation system. It's easier to do it at one time, but you don't have to use it unless you find you don't like the time it takes to get hot where you want.
Good point. I had thought about it but ruled it out since heat pump hw heater is really cheap to run - less than $50/yr and calculated worst case wait times of 11 sec upstair kitchen (25x1.18+4x3.91)/128/2*60) and 8 sec or less for other kitchen and baths (15x1.18+4x3.91)/128/2*60) at 2 gpm. With probable wait time being almost half that if heater to manifold is warm. Which I plan on double insulating. Makes sense tho to run pipe as an insurance/backup plan. How much extra do I leave near manifold and at walls? And what recirc pump+timer should I buy?

Keep in mind that pex can't handle exposure to UV, so if it might see that in the runs, it must be protected...most give you up to 30-days to protect it during the buildout.
Fortunately no issue here - all indoors in basement which I will then insulate once pipes are run.

Code wants all of the hot lines to be insulated, and making them shorter, with one larger one feeding it will make that cheaper and easier, too.
Thanks, good to know! Had that in mind as I was designing and also why I chose groups over single home runs. Which should also help with shorter hot to tap times.

With insulated lines and maybe a timer so it doesn't run when not needed, the wasted water, sewer charges, and energy use can end up less with a recirculation system versus without, and, it effectively makes your WH larger. Think of it this way...you want hot water and it takes 90-seconds to get there first time of the day. Say the faucet uses 2-gallons per minute...that's 3-gallons of hot water you paid to heat that you didn't get to use for its intended purpose. With the lines precharged with hot, you have hot there almost instantly when you open the tap, and the whole tank is full of hot that wasn't diluted with the incoming cold water running the tap without. Depending on where you live, water can be precious.
Good points, makes sense. In my case wait times tho are less per above. Fortunately I also have an 80 gal water heater that is cheap to run, well water that is plentiful even in droughts and an up to date septic system. I will definitely consider and allow for the option of instant hot. Nice luxury!

I would run a larger pipe to your hose bibs...the ID of PEX is going to generate some friction and pressure loss when you ask it to have a high flow. Expansion fittings with PEX-A will have less restrictions in it, and it's more flexible and can handle a tighter bend than types -b or -c. It's also the only one that can be restored if you kink it. The other types require you cut out the kink and substitute a fitting...type -a, with a heat gun, can be restored without.
Was wondering about that. Was leaning toward 1/2 after reading end to end studies on PEX vs copper where they are net equivalent when PEX is allowed to bend vs installed with 90 degree elbows like copper. Going from copper to PEX I will be removing 3-4 elbows for each bib. So I was thinking it would roughly equal out and the friction be less of an issue given less than 40 ft runs. Plus I’m a bit hesitant to have over capacity for bibs since they currently take half or more the house supply with 1/2 copper. Which creates some unhappy people So as long as I have similar bib pressure+flow, which currently pretty good (fill up 2000 gal pool in 3-4 hrs) I’m leaning toward 1/2. Given that, would you still suggest 3/4?

Regarding the list of assumptions+questions, am I off on any, like tee orientations? Will it make a significant difference to run 3/8 off side of 1/2 to sink+toilets so that tub+shower get better pressure+flow? And does NH code allow a side spigot on a tub w/shower to more comfortably allow two to soak together?

Thanks again for the suggestions+feedback.
 
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wwhitney

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My brief thoughts:

3/4" PEX to the hose bibs. If you want to minimize the effect of using the hose bib on the domestic water use, move the split between the two as far upstream as possible (right after the well tank?)

Skip the 3/8" PEX, just use 1/2" PEX. The only upside to the 3/8" PEX is that for a hot water run it will take less time to drain out the cooled water. A negligible benefit if you're talking 5-10' of pipe with the bathroom.

To my understanding (no experience), if you have a CSV, it's not worth upsizing the tank to reduce pump cycling.

The plumbing code may restrict the use of PEX close to the water heater, so you may need a longer copper section at the outlet.

Cheers, Wayne
 

wwhitney

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With insulated lines and maybe a timer so it doesn't run when not needed, the wasted water, sewer charges, and energy use can end up less with a recirculation system versus without, and, it effectively makes your WH larger.
Agree on the wasted water (that and lower wait time are the upsides to a recirculation system), but disagree on energy use. Assuming that for comparison on the non-recirculating system you don't open the tap to drain the cooled water and overshoot the mark wasting hot water.

The rate of energy loss from the hot water piping system depends on its length and the temperature of the water inside. [And also the insulation level and diameter, but let's assume those are the same in both cases.] So an automatic recirculating system that maintains close to hot water temperature in the piping at all times is going to constantly be losing heat at the maximal rate for the system. While a non-recirculating system will have a decaying rate of heat loss in between draws; once the pipes reach ambient temperature, there is no more heat loss.

So to minimize the energy cost of a recirculating system, you want to avoid a dedicated return line, that's just a radiator [But you might decide the upside of a dedicated return line is worth the energy cost, I've not studied the question.]. And you want to use an on-demand type system (press a button), where it recirculates only when you would otherwise be waiting for hot water out of the tap and wasting the cooled water. With both of those features, the energy penalty could zero or close to it. And you'll save water and reduce wait times.

Cheers, Wayne
 

yNotry

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My brief thoughts:

3/4" PEX to the hose bibs. If you want to minimize the effect of using the hose bib on the domestic water use, move the split between the two as far upstream as possible (right after the well tank?)
Thanks Wayne, much appreciated. The split is currently 3ft after the well tank, well before everything else and am planning to do the same. I’m not understanding why the bibs need more capacity since the current 1/2” supplies more than enough pressure+volume whether washing cars, watering lawn, spraying/cleaning or filling the pool (close to 10 gpm). Can you explain?

Skip the 3/8" PEX, just use 1/2" PEX. The only upside to the 3/8" PEX is that for a hot water run it will take less time to drain out the cooled water. A negligible benefit if you're talking 5-10' of pipe with the bathroom.
So the 3/8” won’t noticeably reduce or minimize sink or toilet effect on tub/shower?

The plumbing code may restrict the use of PEX close to the water heater, so you may need a longer copper section at the outlet.

Cheers, Wayne
Thanks, good point, almost forgot. Was planning on using corrugated flexible hose even tho technically I don’t think I need it on electric heater.
 

wwhitney

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I’m not understanding why the bibs need more capacity since the current 1/2” supplies
Switching from copper to PEX, you don't really have the choice to match the existing. 1/2" PEX is smaller in ID than 1/2" copper, and 3/4" PEX is larger in ID than 1/2" copper. So for cold water, rather than downsize, upsize.

So the 3/8” won’t noticeably reduce or minimize sink or toilet effect on tub/shower?
For the tub, I'm going to say that momentary reduction in fill rate is a non-issue.

As for the shower, the way the lav or toilet use would affect the shower flow would be entirely dependent on the flow rate at the lav or toilet. For a 1.0 or 1.5 gpm lav faucet, I don't see the lav's flow rate being reduced by a short section of 3/8" PEX vs 1/2" PEX; it's going to be determined by the intentional flow limiter in the aerator. That means the PEX supply size to it won't affect the performance of the shower.

On the toilet, I could see that it will refill faster with 1/2" PEX than with 3/8" PEX, not sure though. I think the effect would be small, and the resulting effect on the shower flow rate with a 2.5 gpm shower head and a modern pressure balancing or thermostatic valve would be negligible. If I'm wrong you should be able to add a flow limiter to the toilet supply line, rather than rely on a restriction inside the wall.

For cold water, bigger is always better, so there's some argument for making all your cold water manifold runs 3/4" instead of 1/2". Probably not useful, but would certainly reduce the risk that a toilet refill affects shower flow (although I don't think that risk needs reducing).

Cheers, Wayne
 
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yNotry

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Thanks Wayne, explanations much appreciated.

Switching from copper to PEX, you don't really have the choice to match the existing. 1/2" PEX is smaller in ID than 1/2" copper, and 3/4" PEX is larger in ID than 1/2" copper. So for cold water, rather than downsize, upsize.
Thanks for pointing out the difference. Studies have shown end to end flow rates are generally similar when smoothness and lack of elbows are taken into account vs copper. After taking a closer look at the NAHB study, your point on cold is proven out, with pex cold flow underperforming copper 10% or more (ie low flow scenario) per NAHB study: https://www.homeinnovation.com/-/media/Files/Reports/pex_copper_pressure.pdf

For the tub, I'm going to say that momentary reduction in fill rate is a non-issue.

As for the shower, the way the lav or toilet use would affect the shower flow would be entirely dependent on the flow rate at the lav or toilet. For a 1.0 or 1.5 gpm lav faucet, I don't see the lav's flow rate being reduced by a short section of 3/8" PEX vs 1/2" PEX; it's going to be determined by the intentional flow limiter in the aerator. That means the PEX supply size to it won't affect the performance of the shower.

On the toilet, I could see that it will refill faster with 1/2" PEX than with 3/8" PEX, not sure though. I think the effect would be small, and the resulting effect on the shower flow rate with a 2.5 gpm shower head and a modern pressure balancing or thermostatic valve would be negligible. If I'm wrong you should be able to add a flow limiter to the toilet supply line, rather than rely on a restriction inside the wall.

For cold water, bigger is always better, so there's some argument for making all your cold water manifold runs 3/4" instead of 1/2". Probably not useful, but would certainly reduce the risk that a toilet refill affects shower flow (although I don't think that risk needs reducing).
Thanks for explanation and making sense of the interacting effects. Will go with 1/2.

Can you help me on some other details I’ve been trying to find answers:

1) Are bend supports necessary for 1” supply? Or are brackets + plywood good enough?
2) Are bend supports or drop ear supports necessary for 1/2” feeding sinks and toilets? Or are brackets + bracing good enough?
3) Will long bend vs normal 90 elbows make a noticeable difference on the 1” supply?
4) Will replacing the 1” water source 90 elbow with a straight coupling (bend pex instead) make a noticeable difference?
5) Any issue (other than clearance/not bumping) spigot on side of tub w/shower to more comfortably allow two to soak together?

]
 

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1) I don't know if they are necessary, but I have 44 spares lying around, so if you want to pay for shipping I'll gladly send you some. PM me for details. You really only need them when you want to bend the 1" PEX at like a 9" to 12" radius. If you have room to bend it a 18" or 24" radius, 2-3 supports along the bend would be sufficient.

2) You need to decide how you want to handle the supply stops. There's an argument for running the pex out of the wall and using a supply stop that the PEX connects to directly, as it avoids one connection. In that situation I think you'd need some purpose made support bracket to hold the pex bend and support the pex as it comes out of the wall. You can even get short metal tubes designed to slide of the PEX and make it looks like a metal stub out.

I didn't find that argument compelling the last time I did this, so I used 1/2" copper stub outs with a preformed 90 degree bend and an end designed for my PEX attachment system (cold expansion, F1960). Then I used 1/2" nominal compression stops outside the wall.

3) I'm going to say the difference is approximately equivalent to 5 feet of pipe. For a more exact number, looks up the equivalent length of the two different fittings you're comparing.

4) And I'll say the difference is approximately equivalent to 8 feet of pipe. Same on getting a more exact answer. I assume that the equivalent length of the gentle bend of pex using a support is 0', although when I tried to confirm that in some published literature, I didn't find anything.

Cheers, Wayne
 

Reach4

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3/8 PEX and fittings cost more than 1/2, and they are harder to find. Besides the efficiency advantages, 3/8 PEX will be easier to fish through walls. 3/8 OD soft copper is big enough to supply a lavatory or toilet.

I have not worked with 1-inch PEX. I suspect it is fairly hard to bend. PEX is not as flexible as I imagined before ever using it.

I would not worry about adding elbows.

Not all PEX fittings are the same. With the cheaper crimp/clamp fittings, brass fitting ID is bigger than plastic. I am not saying that the difference will matter with 1 inch PEX in practice.

https://www.pexuniverse.com/types-of-pex-fittings
 

jadnashua

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FWIW, most engineered recirculation systems do not run the pump until you have full hot at the sensing point. Yes, you may need to do that in a commercial building, like a motel, etc., but generally, the ones I've looked at for a home, do not. The one I currently have is not adjustable, and it shuts the circulation off when the sensing point gets to 96-degrees, and doesn't turn it back on again until it drops to like 88 or so...I may be off a degree or two on it, but it's in that ballpark...this is to minimize the heat energy losses, but gives you instant warm, and hot many places. In my situation, my upstairs vanity is the furthest from the WH, while the tub/shower is closer. When the timer enables it to run, I'll have warm at the sink instantly, but because the shower is closer, it gets hot quicker. It's only got a very small motor (like 9W), and runs maybe 45=seconds about every 15-minutes or so, depending on the season.

I've seen some run the recirculation until 105-degrees, and my original one that died after nearly 20-years (the check valve died, not the pump, but the company had gone out of business just the year before so I couldn't get the proprietary part, and I didn't feel like modifying things) was adjustable, while the new one is not (although they do make a model that is).

Without the pump (if I happen to get up early before the timer turns it on), it can take like 90-seconds to get hot water upstairs...I much prefer the recirculation! What you do NOT want to do, is over pump it...high velocity, hot water flow can literally erode the pipe from the insides, plus, the pump costs more as does the electricity to run it. PEX has a maximum recommended flow velocity (it's higher than copper's), but on copper, with hot water, it's a maximum of 5fps. With the ID of copper, that's only 4gpm on a 1/2" pipe, and 8gpm with a 3/4". You'd have to check the PEX manufacturer's design guidelines for velocity. Keep in mind that higher velocity also means more dynamic friction, and thus, more dynamic pressure drop.

You may find that hot water recirculation systems eventually become mandatory to help save water. They certainly do that, but if combined with a timer or manual activation, can also save power. Even with your own well, every gallon you pump out of the ground, you're paying for the electricity to pump it.
 

wwhitney

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if combined with a timer or manual activation, can also save power.
They can not save energy as far as heating water. The best you can do is use manual activation to avoid an increase in water heating requirements.

Cheers, Wayne

Edit: OK, that's a little too absolutist. If you can arrange for the recirc to not cause the water in the hot water pipes to be hotter/longer than if you don't have it (e.g. a manual activation system that just pumps the water back into the cold line), so it just does the equivalent of running the hot water to the temperature at which you want to use it, then it avoids increasing the heat load on the water heater.

And then if you also direct that tempered water (at least as warm as indoor air temperature, which is presumably warmer than your incoming cold water) back to your hot water tank, then you do save a little bit of heating required for your hot water. That will be a small effect.

So I need to revise my statement to saying that recirculation almost never saves heating energy.
 
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yNotry

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Thanks Wayne, much appreciated.

1) I don't know if they are necessary, but I have 44 spares lying around, so if you want to pay for shipping I'll gladly send you some. PM me for details. You really only need them when you want to bend the 1" PEX at like a 9" to 12" radius. If you have room to bend it a 18" or 24" radius, 2-3 supports along the bend would be sufficient.
That would be great, thanks! I only have room for 9” to 12” radius bends.

2) You need to decide how you want to handle the supply stops. There's an argument for running the PEX out of the wall and using a supply stop that the PEX connects to directly, as it avoids one connection. In that situation I think you'd need some purpose made support bracket to hold the PEX bend and support the PEX as it comes out of the wall. You can even get short metal tubes designed to slide of the PEX and make it looks like a metal stub out.

I didn't find that argument compelling the last time I did this, so I used 1/2" copper stub outs with a preformed 90 degree bend and an end designed for my PEX attachment system (cold expansion, F1960). Then I used 1/2" nominal compression stops outside the wall.
Thanks, will use ear drop supports. Am planning on PEX direct to supply stops.

3) I'm going to say the difference is approximately equivalent to 5 feet of pipe. For a more exact number, looks up the equivalent length of the two different fittings you're comparing.
I’ve looked but can’t find equivalents for sweep elbows. Which are hard to find as well. You’re approximation is about half the tight 90 lengths which makes sense and is close enough to validate the extra money. Thanks.

4) And I'll say the difference is approximately equivalent to 8 feet of pipe. Same on getting a more exact answer. I assume that the equivalent length of the gentle bend of PEX using a support is 0', although when I tried to confirm that in some published literature, I didn't find anything.
Yes, I’ve seen several references on bend = 0. Which is why PEX w/o elbows ends up similar end to end to same nominal copper with elbows.
 

yNotry

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3/8 PEX and fittings cost more than 1/2, and they are harder to find. Besides the efficiency advantages, 3/8 PEX will be easier to fish through walls. 3/8 OD soft copper is big enough to supply a lavatory or toilet.
Thanks Reach4. Fortunately open walls and no fishing involved. So I can enjoy the savings.
I have not worked with 1-inch PEX. I suspect it is fairly hard to bend. PEX is not as flexible as I imagined before ever using it.
PEX B 1” bends pretty easily to 18” radius but gets harder with 9-12” radius.

I would not worry about adding elbows.

Not all PEX fittings are the same. With the cheaper crimp/clamp fittings, brass fitting ID is bigger than plastic. I am not saying that the difference will matter with 1 inch PEX in practice.
Thanks, tho I think you mean smaller ID. Yeah it may not make that much difference technically but makes a bigger difference mentally knowing I did the best I could. No regrets! Thanks for your help.
 

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Don't see a dedicated line to the recirc system as being a energy waster just gotta have it set up correctly, I'd rather have the return line and be able to adjust it in many different ways a timer , thermostat, or remote. You can set it up the same if you want as one that doesn't have a return , advantage being that if you decide you want a good system you don't need to add a return line later tearing out drywall etc. a 1/2 piece of PEX is real cheap to run now not so much later
 

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Brass fittings used with PEX B have bigger ID than plastic fittings used with PEX B.
Ah, got it. Thanks for clarifying. Thought you were comparing to copper. I’m staying away from plastic fittings, using brass, stainless or copper.
 

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don't see a dedicated line to the recirc system as being a energy waster just gotta have it set up correctly, Id rather have the return line and be able to adjust it in many different ways a timer , thermostat, or remote. You can set it up the same if you want as one that doesn't have a return , advantage being that if you decide you want a good system you don't need to add a return line later tearing out drywall etc. a 1/2 piece of PEX is real cheap to run now not so much later
Thanks Jeff for confirmation. I appreciate all the great ideas + discussion on recirc. But right now I’m trying to keep focused on the upgrading current system. I’m total agreement and will run 1/2” for future recirc options.

My only question which hasn’t been answered is how much length to leave under the sink or shower and then how much to where they return to. Which in my case would be to the right of the hot manifold in my sketch.

And given I will have a hot manifold it sounds like I will want to have a recirc manifold to return to. Then use a temp switch with a timer to keep hot water in pipes between 6am to 8pm. Do I have that right?
 

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Ah, got it. Thanks for clarifying. Thought you were comparing to copper. I’m staying away from plastic fittings, using brass, stainless or copper.
No sense staying away from plastic. They are cheaper. Where you are filling a toilet or sending water to a lav, the 1/2 inch is oversized from ideal anyway. So any slight restriction due to using plastic will be truly not noticeable.

As to how long to leave the stubs, leave them long enough that you can cut them to length when you get to that point. What will you use for the stop valves? Sharkbite works.

I don't know that they have stop valves that you can screw to the wall to fix them in place. I made my own system for the lav, and just let the sharkbite valve feeding the toilet not be secured. After attaching the Sharkbite valve to the PEX, I shoved the valve to push the PEX into the wall.
 

Jeff H Young

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As reach 4 said the plastic fittings cheaper another point is if you like plastic pipe then the fittings should be good too . the smaller ID on the plastic isnt a concern if there arent a lot of fittings and piping is correctly sized. sometimes some of the brass fittings been known to have problems too.
stubbing out whatever convienient 6 inches usually plenty .
as for your future hot water circ plans. the timers often can be set on and off many times per day you can have it only operate a few hours in morning then back on in afternoon , plus have a temp setting. the way you route your piping makes a big differance long runs off the main loop dont get circulated
 
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