First Time Full Repipe, does this sound right?

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Paulcmaine

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My house is fully plumbed with bolybutyl, unfortunately. On the plus side it's post on pier so it's about as easy as it gets - I only need to cut out two small squares of drywall to repipe the entire house! I've done a lot of plumbing before but this will be the biggest job to date. This site seems very kind to homeowners and I would love to hear it if anyone has the time to read this and see if I'm making any glaring errors!

Quick overview - 1400 sq ft house, 2 bath, just two of us living here.
Down here (LA) plumbing is all just run under the house, typically uninsulated! I will be insulating everything with pipe insulation.

All fixtures but two are very close to each other and I will be switching out the old water heater to a 160,000 btu indoor on-demand unit located in the kitchen almost dead center between them all (it fits nicely behind the fridge).

I will also be putting in a 13kw electric unit to run a 1.5 bath (shower no tub) located on the other end of the house.

I have 3/4 iron pipe coming from the water meter to under the house. My plan is to go from that to pex and run pex for everything with copper stub-out fitting for aesthetics and rigidity. I can stub out most fixtures directly through the floor with the exception of a few that will be in the walls. Then propress 1/4 turn valves for fixtures.

Piping will be 1" pex for the trunk line which will run directly to the tankless heater in the kitchen near the back of the house. Along the way I will tee off 1/2" lines for cold water and one to run the electric on-demand for the small bathroom. Then a 3/4 trunk line out of the WH with 1/2 tee'd off to fixtures. I'm borrowing a propress tool for the crimps.

I know there are a lot of mixed opinions about tankless heaters but I'm pretty much set on that decision for a few reasons so not really looking for advice there. However I am also pricing out a/c systems and am slightly concerned that if I go with central I might have a gas supply issue with gas dryer, a furnace and the 160,000 btu WH all located about 50' from the meter on 3/4" pipe. I think that I will be going with mini-splits though in which case this shouldn't be a concern.

Just a couple of questions -
-Any glaring errors or things I'm missing?

-It does freeze here once or twice a year with the occasional hard freeze and the usual approach is just to drip your pipes. Given that I should use Pex-A, right? My understanding is it's slightly less likely to burst if it were to freeze? I'll be using copper crimp rings with a milwaukee propress tool.

-Is it worth the extra cost for copper fittings? I've used both plastic and copper for years on various projects and never had either fail.

-Looking at the small bathroom as an example, I've got a 1" cold water trunk line running along the sill and I need to get 1/2" to toilet, shower, sink and 1/2" to the 13KW electric on-demand and then from there to shower and sink. It's a small bathroom so all fixtures are within a couple feet of each other. Is there a correct and incorrect way to pipe this? My OCD wants to run individual lines off of the trunk with a series of 1"x1/2"x1/2" tees or a 1" x 1/2" (x4) manifold if I can get one but I suppose it would be a couple feet less of pipe to do a 1"x3/4"x1" tee and then a series of 1/2" tees off of that to split to the various fixtures. Is there a 'standard' way to do this or is it just personal preference?
 

Jeff H Young

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I think running a single 3/4 inch line 50 ft to a 160k btu heater will just barely make it . but youll have to size it out I suspect itll be undersize
 

JohnCT

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Insulation - insulating pipes is fine for getting hotter water to a fixture, but insulation doesn't stop heat flow, it only slows it. So if you're not using any water and the pipe gets cold enough to freeze, it will freeze even with insulation. If you get a freeze warning, it's a good idea to drip a fixture to keep fresh water (and fresh heat) in the pipes - even cold water is heat. But yes, PEX is more tolerant to freeze damage than copper, but like having an air bag in your car, it's best not to use it if you can avoid it, and insulation only helps if the freeze is short. If the freeze drags on and there's no water movement in the pipes, they will freeze even if insulated.

I wouldn't press anything on your stubouts. Propress is really a fancy/better Sharkbite without the Bite's single advantage - you can remove the angle stop and push on a new one if the stop goes bad. If you press one on, you have to cut it off. Lots of companies make very good push on angle stops. That's what I did for my new copper stub outs. You can also sweat on a angle stop or use compression, but the Press means you have to shorten your pipe if you service the stop, so if you stay with this plan, make sure you have enough copper coming out of the wall in case a stop fails. At most, you'll get one ProPress stop replacement before having to open the wall to replace the stubout.

Make sure your water heater is copper plumbed into an appropriate mixing valve before transitioning to PEX.

If you're using PEX A, why not just expand the pipe instead of crimp? Expansion is the easiest and most reliable and foolproof way to connect PEX, plus you'll experience less flow restriction.

If your water heaters are any distance away from your fixtures, you could run home run 1/2" from a trunk right after the mixing valve instead of running a 3/4" and branching off close to the fixtures. It's more work and more pipes, but it's the fastest way to get hot water remotely without using recirc. Some people use 3/8" dedicated pipes to hot water fixtures for faster hot water but I've never tried that.

John
 

Paulcmaine

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Insulation - insulating pipes is fine for getting hotter water to a fixture, but insulation doesn't stop heat flow, it only slows it. So if you're not using any water and the pipe gets cold enough to freeze, it will freeze even with insulation. If you get a freeze warning, it's a good idea to drip a fixture to keep fresh water (and fresh heat) in the pipes - even cold water is heat. But yes, PEX is more tolerant to freeze damage than copper, but like having an air bag in your car, it's best not to use it if you can avoid it, and insulation only helps if the freeze is short. If the freeze drags on and there's no water movement in the pipes, they will freeze even if insulated.

I wouldn't press anything on your stubouts. Propress is really a fancy/better Sharkbite without the Bite's single advantage - you can remove the angle stop and push on a new one if the stop goes bad. If you press one on, you have to cut it off. Lots of companies make very good push on angle stops. That's what I did for my new copper stub outs. You can also sweat on a angle stop or use compression, but the Press means you have to shorten your pipe if you service the stop, so if you stay with this plan, make sure you have enough copper coming out of the wall in case a stop fails. At most, you'll get one ProPress stop replacement before having to open the wall to replace the stubout.

Make sure your water heater is copper plumbed into an appropriate mixing valve before transitioning to PEX.

If you're using PEX A, why not just expand the pipe instead of crimp? Expansion is the easiest and most reliable and foolproof way to connect PEX, plus you'll experience less flow restriction.

If your water heaters are any distance away from your fixtures, you could run home run 1/2" from a trunk right after the mixing valve instead of running a 3/4" and branching off close to the fixtures. It's more work and more pipes, but it's the fastest way to get hot water remotely without using recirc. Some people use 3/8" dedicated pipes to hot water fixtures for faster hot water but I've never tried that.

John

Thanks John, appreciate you taking the time this is very helpful.

I grew up in Maine so very familiar with freezing pipes! A true hard freeze is so rare here that the exposed piping isn't much of an issue but since most houses are post on pier with all the lines under the house so where people tend to run into trouble is the combination of wind and cold. With insulation you only have to run the pipes maybe once or twice every three winters.

Thank you for the point about the stubouts, I hadn't thought of that you probably saved me some frustration down the line! I will sweat them instead, or just get some quality push fittings.

The crimping is because I have access to a nice crimp tool but not to an expansion tool, I would use it if I had it. Should I just stick with Pex B if I'm crimping?
 

JohnCT

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The crimping is because I have access to a nice crimp tool but not to an expansion tool, I would use it if I had it. Should I just stick with Pex B if I'm crimping?

Doesn't matter because A can also be crimped, so the fastening system wouldn't determine the pipe when crimping.

There is however a bit of anecdotal evidence that *suggests* that B might be the more long-run durable pipe, so if you're going to crimp anyway, and you don't need the tighter turn radius of A, then B might be the better option.

BTW, some B manufacturers now certify their pipe for A type expansion using the less restrictive F1960 fittings. Power expander tools aren't really that expensive and considering the scope of the project of your repipe, it's not a bad thing to own for any future work or additions - or to satisfy your XY chromosomes in owning more tools.. :p

I bought a Milwaukee M12 with two heads for my repipe and kept them. Originally I planned to sell them and regroup 90% of the cost but decided to keep the tools instead.

John
 

Jeff H Young

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under a house almost no joints are buried pretty simple build Personally Id go expansion joining type A. I guess type b expansion or crimp 2nd and third choice for me type b Im not sure whgich is better expansion or crimp but I think crimp fittings suck , the ID is small a small job like this though sized properly it shouldnt be a big deal .
rats like plastic pipe btw.
 
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