This is related but somewhat separate to water heaters.

Installation orientation: It sounds like the recommended orientation is w/ the pipe fitting down with the air bladder valve up, allowing for sediment to drain out rather than settle down on the bladder. Other orientations (horizontal or pipe fitting up) are okay if necessary but suboptimal. Is this the consensus opinion here?

Isolation valve: I was thinking an isolation valve (separate from cold water supply valve) would be nice) - a ball valve between the tee and the expansion tank to allow the tank to be replaced without affecting the cool water supply to the hot water heater. Perhaps important not just for replacements but also if there is an issue w/ the tank (leaking, broken, whatever). BUT, the plumber didn't recommend it and prefers just to attach the tank to the tee. Also, the Amtrol turbulator seems to want to have the diverter part in the cool water supply line to function, which doesn't allow for an isolation valve. Thoughts? Isolation ball valve for the expansion tank or not (if no valve, then one must shut off the cold water supply valve upstream of the tank, and perhaps drain the water heater a little as well as vent it in order to replace the expansion tank)?

Brand: sounds like the primary residential brands are amtrol and backstop. I was leaning toward amtrol but the plumber quote prefers backstop (not sure if it's product based or plumber profit based). Sounds like these need to be replaced every 5-10 years so may not matter much. And relatively easily replaced DIY. But any strong preferences for one or the other? Indifferent?

If parts are available, going to try to get this done next week.

In my last house it was installed horizontal. This place it's vertical. Whatever....

This is my State Water Heater installation from 10 years ago, installed by me personally in early spring (late winter?) 2016. The install was done overnight, and by the time the morning rolled around, there was hot water available for my wife & son to take showers before work/school. My home is a two story colonial and the water heater is located in the basement, which necessitated shutting off the water and draining hot and cold water plumbing for the whole house during the install.



I used SharkBite fittings and SharkBite braided stainless Water Heater supply lines, as I didn't want to sweat fittings onto the copper pipe, which transitions to Wirsbo Pex Tubing on the other side of the hanger, as shown in the first pic. The original Water Heater was installed by the builder's Plumber without a Thermal Expansion Tank, which IMO led to a premature failure of the original State Water heater. I installed the WATTS Thermal Expansion Tank, relocated the Vacuum Break/Relief Valve, completely reworked the PVC Exhaust Piping, AND reworked the Natural Gas Supply Piping as well.

Too bad the 'Licensed Plumber' didn't install the Water Heater correctly in the first place as it likely would've lasted a lot longer, though after doing the math from when we got our C.O., it did last 10 years. His excuse on the omission of the Expansion Tank was that he had installed an Amtrol Expansion Tank on the supply to my Hydronic Boiler (seen in the background of the second pic), and called it good. I'm no 'Licensed Plumber' but, this was despite the fact that I was getting weeping from the PRV (Pressure Relief Valve) on the Water Heater, and high pressure surge/relief at the cold water faucets throughout the house!

Re: orientation of the expansion tank, well, it depends. I've seen them mounted multiple orientations. In my case, with the pipe up against the floor joists/insulation and using a SharkBite fitting, 'right-side up' (connection up) was the way to go. Honestly, if the bladder fails and the expansion tank fills with water, I'm sure I'll be quite happy the connection is up when I remove & replace it! Perhaps most importantly, it should also be noted that with the connection down orientation, all the labeling on the expansion tank would be upside down...Just Sayin'

ETA - Add'l relevant detail

This message has been edited. Last edited by: nhracecraft,

Plumbing looks nice and clean. I hope my is like that.

Noticed that the orientation is connection up; I'm trending toward connection down. Unless the stickers are applied to the tank after installation, it's weird that they are right side up if connection side down is the recommended orientation.

Anyway, seems like you guys aren't using an isolation valve for the expansion tank - just attached directly to the tee.

Okay, maybe I'll go that route.

Doesn't really matter, go for piping convenience.
You're installing on the hot side, so any sediment should already be out of the system. Of course you also have a large, low velocity tank right before it for the sediment to settle as well.

Well expansion tanks are usually before any filtration, so are more susceptible, but again, the sediment is a problem to solve separately. Mine does build up sand & then blows it out when I'm using a lot of water from my shop (Shop is Tee'd off the main line before the house). It fills up the trap/filter in the shop quicker, but at least the bladder gets cleaned out. This is usually only noticeable when it's dry & the 6 irrigation wells around me are pumping hard. Otherwise, our water is pretty clear.

I don't know why you would need an isolation valve. If the bladder fails, shutting the water off & draining to service/inspect the rest of the system is probably a good idea anyway. if you don't want to back-drain the system, put the shut off downstream of the tank

quote:

Originally posted by snidera:
Doesn't really matter, go for piping convenience.
You're installing on the hot side, so any sediment should already be out of the system. Of course you also have a large, low velocity tank right before it for the sediment to settle as well.

Well expansion tanks are usually before any filtration, so are more susceptible, but again, the sediment is a problem to solve separately. Mine does build up sand & then blows it out when I'm using a lot of water from my shop (Shop is Tee'd off the main line before the house). It fills up the trap/filter in the shop quicker, but at least the bladder gets cleaned out. This is usually only noticeable when it's dry & the 6 irrigation wells around me are pumping hard. Otherwise, our water is pretty clear.

I don't know why you would need an isolation valve. If the bladder fails, shutting the water off & draining to service/inspect the rest of the system is probably a good idea anyway. if you don't want to back-drain the system, put the shut off downstream of the tank

Installed on the cold inlet

My plumber said horizontal is ok.

Jmho as a total amateur, vertical makes the most sense. Ideally it runs half full of water and half air, separated by the flexible membrane. It will be less stretched if mounted vertical, and thus seemingly less likely to fail.

A ball valve would be a convenience for future expansion tank replacement. Is it worth the cost to pay your plumber to do it?

I see some recommendation on the webz for installing an isolation valve. But I can't find any mention in expansion tank installation guides nor images / videos of any installation with an isolation valve.

It seems like it would be useful to me since this is a part that needs occasional replacement. But I guess most people just shut off cold water supply, drain the water heater a little and then remove the expansion tank.

I'll go with the majority I guess. I think the isolation valve would only be another $50-100. But I'll go without this time. I think it's an easy retrofit later if desired (when I replace the expansion tank).

Vertical seems recommended but I'm confused with the wording. I can't determine if the water connection down or water connection up (above the expansion tank) is preferred. It sounds like connection up is preferred as it makes the water flow down and displace the air; connection down may allow for an air bubble in the expansion tank. At least that what it sounds like when I read it but not sure.

If connection up is preferred, the plumbing is currently flush with the water heater top; the water line will need to go up then come back down in order for the expansion tank to be connection up (and above the water heater).

Perhaps the expansion tank can be installed along side the water heater, allowing the water line to be flush along the top of the water heater. That would make replacement easier too.

Water connection down. There is a rubber-like membrane that runs across the middle of the tank. With the air valve on top and the water connection on the bottom, you pressurize the tank so that the top half is air and the bottom half is water, with the waterproof membrane separating them. If the water pressure increases, the membrane stretches upward a bit, and when the pressure decreases the membrane stretches down a bit. Thus any transients get absorbed by the air in the tank.

If you mounted it upside down with the water connection up, the water would try to go down to the bottom of the tank, causing that membrane to contort crazily.

I get what you're saying. But still confused by what amtrol and the webz say; there seems to be contradiction even with amtrol documents. You'd think such a simple appliance with years of experience, one could write clearly what is the preferred installation.

Amtrol docs seems to indicate that vertical installation is preferred but horizontal is acceptable assuming proper support. There seems to be a preferred orientation to optimize product life; other orientations may be functionally okay but may compromise product life.

So, I get vertical orientation is preferred. But water connection up or down?

Up: seems to prefer relief of air in the water line; any air in the expansion tank (where water is supposed to be) can naturally expelled. However, this orientation also seems to allow sediment to settle on the bladder which is not considered a good thing for product life. Also, easier to replace without dumping water when disconnecting the tank. The Up orientation seems to be the default image (as typical or recommended; Down was indicated as optional orientation) on all the Amtrol installation guides.

Down: seems to prefer prevention of sediment settling on the bladder. But may allow for air to be trapped in the water area. Not sure if this is really a bad thing or not; perhaps depends on how much air gets trapped. But this seems to dump water from tank when disconnecting for replacement unless you drain the water heater a bit (which seems advocated anyway).

Confused...

Text from Amtrol manual:
For the best tank performance, mount with the water connection up in accordance with Figure 2. If it is not possible to mount in the recommended position, inverted or horizontal mounting is permissible.

An isolation valve would be perfectly fine, but unnecessary except in the case the expansion tank fails or leaks. They can and do. I would replace the expansion tank same time as the water heater anyway as a best practice. I seriously doubt if you have enough settlement to matter towards orientation if on public utility water... a straight up, connection at the bottom orientation would be the logical choice regardless, but the tank will function in any orientation perfectly. It may be required by code, but unless there's a check valve, pressure reducing valve, or water filtration system. The tank is completely unnecessary as pressure will simply back down the main line in case of any heated water expansion. As a retired former plumber, years ago, I can assure you there are more houses without one than there are with one.

Okay. Sounds like all orientations are used regardless if there is an OEM preference / recommendation. Instead of encouraging the plumber one way or another, I'll just leave it to him to decide which is best (hopefully for function and not for his ease of installation).

The tank is required by code here even though I haven't had one for 25+ years without issue. I don't think sediment is an issue w/ our water - it's pretty clean and soft. Unless there is some exception circumstance / event.

There is a regulator / pressure reducing coming off the main line going toward the house. The pressure at the house is 45-60psi (depending on time of day).

Okay, let's call this done.

Next decision is whether to get the BW URG150 or URG250 model. I think the 150 is sufficient for our needs but not sure if the higher BTU 250 model would be good to install for an extra $300. It's a 10% adder to current total cost.

Well, the heater and the expansion tank are installed. Looks like a professional job.

Dumb question about the expansion tank: the supply line varies from 45-60psi throughout the day. The tank is pre-charged to 50psi (albeit unconfirmed empirically). What should the charge be given the variance in supply pressure? 50 psi okay?

Also, it may have been like this all along but I'm just noticing that the cold water supply line actually feels warm from the top of water heater back to the ball valve (about 2' of plumbing). Is this normal? I think it's just conducting heat from the hot water in the water heater but not sure if this is normal or not.

^^ Sounds like your Expansion Tank needs more pressure/charge than it has currently. On my Water Heater, the Cold/Supply connection nipple is warm as is the threaded collar on the supply hose that is connected to it, but the supply hose itself, even immediately after the threaded fitting is NOT warm at all.

Your plumber should have measured the actual pressure with a gauge (usually done at a hose bib) and adjusted the pressure in the Expansion Tank accordingly. I did this when I installed mine, which was in the middle of the night (3:30 AM?), so if the pressure varies here, it was likely at it's highest/peak during that time frame. My WATTS PLT series Expansion Tank came with a Pre-Charge of 20 PSI and I had to increase the charge pressure in the Expansion Tank BEFORE installing it. I'm not 100% sure if I had to match the static pressure I measured at the hose bib or just have it in an appropriate level based on a table in the installation guide. Regardless, if he did that, it might be worth a call tech support at Amtrol to get further guidance.

Thanks!

Never mind - I'm an idiot. I measured temps on the supply line. Where I said it was warm, it's actually downstream of where the recirc line attaches to the supply line. So stupid me, it should be warmer than the rest of the cold line. The cold line upstream of the recirc intersection is a bit cooler.

Still, I'm going to check w/ the plumber and see if the charge pressure is correct for my installation. The pressure is low (45 psi) at night and higher (60 psi) during the day (for about 6 hours, at least during summer). The 'average' pressure is about 50 psi, which matches the pre-charge (assuming it's actual).

Anyway, will be calling the plumber.