tankless water heater question

[corvairbob]

say guys i have a new house being set o my foundation and the plumbing is all stubbed thru the floor with pex. i'm going to ahve a high efficiency 7.5 GPM residential 180,000 BTU natural gass tankless water heater i beleive it is a non condensing unit also because in the extra section just below the item it shows a non condensing vent. it will need some valves called threaded plumbing installation valve kit.

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so it seems the plumber the contractor has to do this told us that it needs a flush kit and a bunch of other stuff besides the thru the roof vent kit.

i was under the impression that this unit from lowes came with the necessary items to install it besides needed the valve kit.

that plumber wants an extra 4,000$ just to get the unit plus the items for installing it. i can get it at lowes for 800$ he wants more and then he said he will not warranty it if i get the unit.

so tell me is this about correct or might he be padding the pocket because he will be working in a 40" crawl space? and an attic to install the vent thru the roof.

the unit is a rinnnai unit internet # 306655590 model # V75iN if that helps

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[Fitter30]

This heater takes a special flue not pvc also page 16 also calls for valves to flush the heat exchanger. Page 26 charts top is pressure drop bottom is gpm to temp.
This heater isn't that difference for a condensing has inherent some of the same maintenance flushing the heat exchanger and using a more expensive flue material. Yes heater will flow 7.5 gpm at 25° water temp difference. For design need two things. Max gpm flow and coldest water temp. If water temp is 45° and wnt 120° has a 75° rise. On the chart shows 4 gpm. Personally wouldn't warranty anything i didn't purchase for the job. If unit wouldn't startup not my problem, need another fitting it would be a extra.

https://www.google.com/url?q=https://media.rinnai.us/salsify_asset/s-43d60415-4de7-4ad8-aa59-1b39248bfe09/100000258-Value%2520Series%2520Installation%2520and%2520Operation%2520Manual.pdf&sa=U&ved=2ahUKEwi4rPnsguiOAxVR6ckDHZ0hBhcQFnoECAoQAg&usg=AOvVaw2_1DznTqUbRNFzoCOH4yx_

 

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[Breplum]

I highly recommend condensing tankless. Why not go for 96% AFUE. They typically use PVC vent pipe, so you save considerably on venting and simplicity of installation. Take the $ you would waste on special vent and labor and just go with the Super High efficiency. I prefer Navien.
Just have to dump the condensate to grade. 40" crawl space is a terrible place (done a quite a few) for a tankless. Running descale in that space is unpleasant to boot.

 

[GReynolds929]

Your gonna want a 199k btu condensing unit being in Michigan. Your groundwater is too cold to get decent flow rate otherwise. Depending on demand you might need two. If 4k is the installed price that's not bad, I don't warranty anything I don't supply either.

 

[corvairbob]

ok what is odd for warranty is he is going to install it and he is not going to warranty it for more that the factory does. so now i not only have to pay double the first quote i have to pay double for the same heater. i believe i will just get an elect and set that in the crawl space as the power is all ready at the heater location and just have him connect the pex to it being he has to finish the connections anyway. also i'm now looking into just reinstalling the old heater it is 2 years old and have the furnace guy set up the roof vent with connections for both the heater and the furnace and if he says he can't run both in the same exhaust then just do 2 roof vents. but being they are both gravity venting they should be able to connect to the same roof vent. they were that way before.

the old heater never saw smoke or fire or water from the fire i drained it the next day it never had water in it since. and the room it will go into is vented for the dryer. the apt i'm at now has the washer dryer and heater in the same room and the heater is in a corner 5" from each side. so if i have that room i may just reuse that heater it is a 40 gal tank a.o. smith unit. anyway thanks for the advice on this

 

[Breplum]

A condensing tankless uses a draft inducer, so only sidewall termination is necessary.

 

[corvairbob]

thanks that explains why the unit i posted showed a side type vent. so what i'm going to do now is put one down in the crawl space next to the 40 gallon electric i just set there. and install it next to an outside wall so the draft inducer will then vent to the outside. and then i have a drain located in the floor at that location and the main plumbing will be located there also. and the electric i just put there will then become a backup if the tankless ever fails. then not roof venting. i forgot the new furnace will not be roof vented. thanks for the help and brain jogging

 

[corvairbob]

another question. the house builder used pex. i asked for pvc-cpvc and they do not use that. anyway i was under the impression they were going to plumb the house complete. all they did was stub the house. so i'm thinking i will pull the pex stubs out and just redo it in pvc.cpvc or maybe all cvpc and just junk out the pex. this way i can make modes if needed without getting all the tools needed for just this one job.

 

[Reach4]

another question. the house builder used pex. i asked for pvc-cpvc and they do not use that. anyway i was under the impression they were going to plumb the house complete. all they did was stub the house. so i'm thinking i will pull the pex stubs out and just redo it in pvc.cpvc or maybe all cvpc and just junk out the pex. this way i can make modes if needed without getting all the tools needed for just this one job.

PEX tools can be cheap.

 

[GReynolds929]

no offense intended, but you have no idea what your doing with the plumbing and should not be messing with it IMO.

 

[corvairbob]

i never messed with pex. so i'm going to remove it and install cpvc and pvc then i do not need to mess with it. i know pipe copper and pvc real well worked with that for years. but never messes with pex. all the mfg did was stub it out 3' for each line. it will not hard to replace it and do it my way. thanks.

 

[GReynolds929]

PVC is not to be used inside the house for water distribution, CPVC is fine just gets really brittle with age and heat. I personally would leave the pex, but to each his own.

 

[corvairbob]

you know it is strange the you say pvc can't be used inside a house for water because they are still building home in my area with pvc. i do know it gets brittle over time. but that also holds true for drain pvc. if i go that route with pvc i will use cpvc for both. so then i will not have to get 2 types of materials. also who is to say pex will not do the same over time. the pvc i installed 30 years ago was still pliable but the pvc used when the house was build was 20 years older and the washer drain broke just by pulling it out about 1" from the wall to remove the panel behind it, so i guess we will see. thanks

 

[corvairbob]

i contacted the local plumber inspector and he said i can do a tankless in the crawl space and direct vent it outside per mfg instructions in the system manual. and then just hook up the water lines and the valves the unit requires for service and operation. and it should be just fine. thanks

 

[zomiee333]

The big difference from the unit is 800$ at Lowe’s is that a non-condensing install eats materials and time: a dedicated roof vent, isolation/flush valves, possibly upsizing the gas line, plus work in the crawlspace and attic. Many installers won’t warranty something the client supplies (that’s standard). I used Ferrer Plumbing in GR; they did a proper start-up and explained the maintenance. Ask for an itemized quote and compare the same parts list, otherwise it looks like they’re padding the price when you’re actually comparing apples to oranges.

 

[corvairbob]

The big difference from the unit is 800$ at Lowe’s is that a non-condensing install eats materials and time: a dedicated roof vent, isolation/flush valves, possibly upsizing the gas line, plus work in the crawlspace and attic. Many installers won’t warranty something the client supplies (that’s standard). I used Ferrer Plumbing in GR; they did a proper start-up and explained the maintenance. Ask for an itemized quote and compare the same parts list, otherwise it looks like they’re padding the price when you’re actually comparing apples to oranges.

thanks i have the gas line sized to the heater at the location and the plumbing. as for installing i will do that it is easy enough being the floor is a cement floor and i ride around the floor on a set uptight creeper. now i'm using an electric water heater but next summer i plan on installing a vent less and switching over to that and draining the electric after pulling the disconnect of course. and keeping it there for a backup if ever needed. the furnace guy suggested leaving the water on to the electric and using it for a water temp moderator tank at least for winters. but then i will still need to flush that out every month or so for any rust collection and sediments. the tankless i'm going to install will be a condensing unit so i can vent it thru the outside wall with pvc like the furnace is now. the furnace guy said it will work just fine. plus i can install flush valves at that outside wall and flush it a bit every month like i do with the electric unit now. thanks

 

[Fitter30]

Pipe the electric wh with two three way T style ball valves then when adding condensing wh the electric can be valved off water will by heater. Then in and out of heater can be drained 100% left open and will dry out. Then if needed with turning the valves can be back in service. Filled ,flushed to get all air out and then powered.

 

[corvairbob]

thanks i was planing on leaving the drain open. but as your saying it will not hurt to also leave the hot-cold open. when i install the tl and put the el. in standby i will cut into the pex and add those valves. good idea.

 

[Fitter30]

thanks i was planing on leaving the drain open. but as your saying it will not hurt to also leave the hot-cold open. when i install the tl and put the el. in standby i will cut into the pex and add those valves. good idea.

Open the relief valve breaks the vacuum draining the tank. Three way valves come in two configurations. Need the T style.

 

[corvairbob]

yes i'm familiar with those just did not think of installing them. and opening the relief to let in air to make it drain. thanks.