Installation check - water to my tiny house


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Old 07-12-16, 11:28 AM
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Installation check - water to my tiny house

My cabin is almost done... Literally days away. I am going to run electrical and plumbing (plumbing first!) as I can run an electrical extension cord for now. Here's the plan, according to viega PEX plumbing products...

2" main will have a ball valve installed and a 1" PEX line will go the last 15 feet or so underground to the cabin. I'll use their "high end" for this 15' or so that is UV stabilized and paint/insulate the exposed so it doesn't degrade. I will have skirting on but it will take some time to get it out of indirect sunlight.

1" main through the flooring into a small closet with an electric slim tank hot water heater. I will T-connect the main line to the cold side of the tank and to a viega minibloc (6 cold/4 hot model). I will mount this miniblock on the wall within about 2-3 feet of the hot water heater (as close as I safely can).

From the hot side out of the hot water heater, I'll go to the 1" hot input side of the viega miniblock (4 hot lines output).

I will run 1/2" PEX hot/cold (red and blue) to shower/tub combo, bathroom sink, kitchen sink, and washer dryer. (4 hot and 4 cold)

I will run 1/2" PEX cold only to the toilet and to an outdoor hose bib. (2 more cold only lines meaning 6 total cold).

Options would be to run a larger diameter line (3/4") from the viega miniblock to the bathroom and T it for tub/shower and sink. I guess I could also use 1/2" here as in the small bathroom there won't be any time where shower and sink are in operation at same time (small bath for 1 person). Or, I could use another miniblock 3/2 locally in the bathroom under the sink or behind a wall panel to cut the pipe runs and use a smaller miniblock in the closet.

That would be all of it...

Any critique, concerns, or doing anything wrong?
 
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Old 07-12-16, 02:45 PM
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I would make all my home runs of 3/4", then turn up to the individual appliance with 1/2". It will help with water delivery, say when someone flushed a commode.

Is the Viega system less expensive than standard ring PEX connections? It looks formidable in price. Is there a reason for its use?
 
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Old 07-12-16, 05:37 PM
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It is quite formidable in price, lol. I see others running a 3/4" PEX line from the main to an "area" like the bathroom and then 1/2" the last few feet. I assume just using pex T connections with crimp rings would get that done.

I designed my cabin so that the bathroom, kitchen, and laundry/hot water are all along the back wall with the hot water heater on one end. If I could get away with a single 3/4" pex line off the hot water heater that runs through the kitchen and then to the bath and t-off of it for the shower/tub, bath sink, and kitchen sink, then do the same for the cold side, it would be very easy and very cheap.

I have read that when doing this type of install, using the kitchen sink, for example will have a lot more impact on the shower than it would in a manifold-type setup.

Bottom line is I want to do it well the first time so I don't have any issues. There's a lot of ways to get to the finish line, obviously, but I'm looking for good, fast, and relatively inexpensive.
 
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Old 07-13-16, 03:23 AM
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Making a single run is less expensive. Remember all your final hoses to the sinks and toilet are 3/8" nominal size. So at any point they are only using 1/2 of the capacity of the 3/4" supply of water, including the kitchen sink. The shower will have 1/2" piped to it, so it will have the most draw in volume at one time. So, activating any other appliance will have minimal affect on the shower, provided it has 3/4" supply at least to a turn up point.

good, fast, and relatively inexpensive
Three words that don't exist combined in the construction industry. You can have each individually, but not together.
 
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Old 07-14-16, 10:05 AM
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Yes, I'm aware of the axiom, "Good, Fast, Cheap. Pick any two." I added the "relatively" in there for that reason, lol.

That said, it appears you are suggesting I run:

1" from the main which I would t-split at the hot water heater with a 1" to the HW heater and then a 3/4 cold and hot line running from the hot side and the t-junction of the main. It would literally be a straight run through the kitchen to the bathroom. I would have a hot/cold turn up at the kitchen sink on the way (no dishwasher), a turn up at the bathroom sink for hot/cold, a turn up at the toilet for cold only, obviuosly, and then a turn up at the shower/tub combo valve and that one would be 1/2". Are 3/8" turn ups OK everywhere else? That's an awfully thin line and I've read that can be an issue but it seems like maybe that's for long runs and not turn-ups...

Thanks again.
 
 

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