Forcing hot water tank fill

[marter]

We just returned from 4 nights in our 2008 19' International and ran short of fresh water the last day (no water hookups at site). Without turning this into a water conservation thread (I've read many helpful threads) my question is how to fill the hot water tank before leaving.

We have a 23 gal fresh water tank, and I believe our hot water heater holds 6 gals. I realized when we returned and was draining the tanks that I only took 23 gals with us instead of 29 gals if I had forced the hot water tank to fill before leaving. Doh.

So if I fill our fresh water before leaving, turn on the pump and run some water through the hot side of each faucet, then top off the fresh water tank will I be carrying the maximum amount of water I can? Do i need to turn on the heater or will it fill automagically?

Thanks in advance,
Mike

[Shacksman]

Originally Posted by marter

We just returned from 4 nights in our 2008 19' International and ran short of fresh water the last day (no water hookups at site). Without turning this into a water conservation thread (I've read many helpful threads) my question is how to fill the hot water tank before leaving.

We have a 23 gal fresh water tank, and I believe our hot water heater holds 6 gals. I realized when we returned and was draining the tanks that I only took 23 gals with us instead of 29 gals if I had forced the hot water tank to fill before leaving. Doh.

So if I fill our fresh water before leaving, turn on the pump and run some water through the hot side of each faucet, then top off the fresh water tank will I be carrying the maximum amount of water I can? Do i need to turn on the heater or will it fill automagically?

Thanks in advance,
Mike

Yes turn on the pump and it will fill the water heater. DO NOT turn on the water heater before the tank is full or you can burn out the element.
PS it's not a hot water heater. It heats cold water.

[pcskier]

Originally Posted by marter

So if I fill our fresh water before leaving, turn on the pump and run some water through the hot side of each faucet, then top off the fresh water tank will I be carrying the maximum amount of water I can?

Yes. But keep in mind, assuming trailer gets winterized and hot water tank was drained and bypassed (assuming this is the case in Nebraska)...once you fill it the first time in the spring, it stays full of water all season, even if you run the fresh water tank dry. If that was the case, you did leave home with 29 gallons of water. Unless for some reason you choose to drain the hot water tank between trips. Some people do, I don't. It's just water sitting in there.

[marter]

Originally Posted by Shacksman

Yes turn on the pump and it will fill the water heater. DO NOT turn on the water heater before the tank is full or you can burn out the element.
PS it's not a hot water heater. It heats cold water.

Good point on the element burning up. Better point on the HOT water heater. Got me there.

[marter]

Originally Posted by pcskier

Yes. But keep in mind, assuming trailer gets winterized and hot water tank was drained and bypassed (assuming this is the case in Nebraska)...once you fill it the first time in the spring, it stays full of water all season, even if you run the fresh water tank dry. If that was the case, you did leave home with 29 gallons of water. Unless for some reason you choose to drain the hot water tank between trips. Some people do, I don't. It's just water sitting in there.

For some reason I've been draining it each time I drain the fresh water. Probably don't need to. When we bought the trailer the PO told us to flip the pop off valve before hitting the road, I assume because it's under some pressure. My brain says if a little is good, more is better, so I went the next step. I'll stop draining it each trip.

My main question is when it fills completely. With a full fresh tank, running a little from the hot side of the faucet will fill it completely vs. just letting it flow through to satisfy the draw?

Thanks,
Mike

[marter]

Originally Posted by Shacksman

Yes turn on the pump and it will fill the water heater.

Rereading Shacksman's response, sounds like that's my answer. Just turning on the pump.

Thanks to all,
Mike

[pcskier]

Originally Posted by marter

For some reason I've been draining it each time I drain the fresh water. Probably don't need to. When we bought the trailer the PO told us to flip the pop off valve before hitting the road, I assume because it's under some pressure. My brain says if a little is good, more is better, so I went the next step. I'll stop draining it each trip.

My main question is when it fills completely. With a full fresh tank, running a little from the hot side of the faucet will fill it completely vs. just letting it flow through to satisfy the draw?

Thanks,
Mike

There is no reason to open the pressure relief valve, except in the fall to drain the tank more quickly. Even then I don't do it. Those things can be notorious for having trouble reseating when opened...you could wind up with a leak at some point. You can just open the hot water side of a faucet before travel (with pump OFF, which it always should be when under way) if you want to relieve pressure from the hot water tank.

Part two, yes, if water comes out of a hot water faucet with the pump on (or on city water connection before leaving home), the tank is as full as you'll get it. There is some empty air space at top of tank to allow for expansion when hot.

[rmkrum]

Do keep in mind that that 'spare' 6 gallons in the water heater is inaccessible unless you remove the drain plug from the water heater--it does not really buy you any usable water.

Once your pump has sucked up as much of the 23 gallons in your fresh tank it can reach (less than 23 gallons typically) and starts sucking air, the water in the water heater just sits there...

I got rid of that unusable water and it's 42 pounds of extra weight by going to a tankless water heater, since those 6 gallons are not easily reachable. I carry bottled water instead...

[pcskier]

Originally Posted by rmkrum

Do keep in mind that that 'spare' 6 gallons in the water heater is inaccessible unless you remove the drain plug from the water heater--it does not really buy you any usable water.

But if he leaves home with a full fresh tank without first filling the water heater (which is what he was doing...draining the hot tank between trips), then his 23 gallons will become just 17 total gallons of accessible water when he gets out in the field and turns on the water pump. Leaving home with both tanks full = 23 gallons of accessible water; Leaving home with just fresh tank full = 17 gallons accessible (unless bypassing water heater). But I know you know this...you might have missed his post stating that he was heading out into the field with an empty water heater.

[rmkrum]

Yup. Missed that. But if I’m worried about water I fill full, bleed air out of system, and top off tank to overflowing. That way I can get max usable.

[OTRA15]

Originally Posted by rmkrum

Yup. Missed that. But if I’m worried about water I fill full, bleed air out of system, and top off tank to overflowing. That way I can get max usable.

One more slight clarification, maybe, for those who may misinterpret "bleed air out of system," . . . .

. . . you just mean that you run all the hot and cold faucets/showers/toilet/etc. until no air comes out. In other words, the water supply pipes are full of good usable water. In an AS with a water heater that holds 6 gallons, this would be included in the grand total, as pcskier calculated, although opening the drain valve would be the only way to "use" this water when the fresh water tank is empty [in an emergency perhaps].

Have a good weekend!

Peter

[marter]

Again, thanks for the replies. Pcskier is correct in that I've been leaving with an empty water heater tank, and filling it later when we setup camp and turn the pump on.

I thought based on this forehead slapping revelation I was gaining 12 gals of usable water by turning on the pump and then topping off the fresh tank. I wasn't considering the fact that when the fresh is empty there's nothing to push that water out of the heater tank, so in fact it is unusable. Learned something there. At least now I'll have all 23 gals ( or whenever it starts sucking air) instead of the 17 gals. we've been getting.

We were doing better on conserving water than I thought.

Thanks all,
Mike

P.S. thanks for the tip on the pressure relief valve, I'd much rather learn the easy way vs. the hard way. And understood on bleeding off the air.

[GammaDog]

I drain my water system completely if I'm storing the trailer for a couple of months or more. I sanitize and refill before my next trip. The nylon drain plug on the Atwood only lasts so long before it needs to be replaced. As an alternative, I put in the Camco water heater drain (a petcck in plumbing terms). Although I never thought of it, this is not only a convenient drain, it would allow the contents of the water heater to be poured by the glass in the event the zombie apocalypse hits while we're seeing America!

https://www.walmart.com/ip/Camco-Wat...Valve/29764281

[OTRA15]

Tank you!

[pcskier]

Originally Posted by OTRA15

Tank you!

Ba-da-bump.

Re: Draining hot water tank mid season between trips. If you were to leave home for a month or more, would you empty your 40 or 50 gallon water heater in your home, or just let it sit there full of water (maybe turned off or on 'vacation mode') and simply carry on when you get home?

[rmkrum]

It depends. I’ve lived places where the mineral content of the water and it’s pH caused water heater contents to be real stinky until flushed. Sitting for 2-3 weeks was enough to make a hot shower a smelly experience. It was a good idea to drain and flush if you let it sit too long.

[marter]

Originally Posted by GammaDog

I drain my water system completely if I'm storing the trailer for a couple of months or more. I sanitize and refill before my next trip. The nylon drain plug on the Atwood only lasts so long before it needs to be replaced. As an alternative, I put in the Camco water heater drain (a petcck in plumbing terms). Although I never thought of it, this is not only a convenient drain, it would allow the contents of the water heater to be poured by the glass in the event the zombie apocalypse hits while we're seeing America!

https://www.walmart.com/ip/Camco-Wat...Valve/29764281

Theres a petcock on my brass drain plug, which is what I've been using to drain the tank. Must have been installed by PO, unless AS did that in 2008. Mine is definitely not plastic.

Thanks,
Mike

[GammaDog]

Originally Posted by pcskier

Re: Draining hot water tank mid season between trips. If you were to leave home for a month or more, would you empty your 40 or 50 gallon water heater in your home, or just let it sit there full of water (maybe turned off or on 'vacation mode') and simply carry on when you get home?

Well... at home we have only tankless water heaters, but that's a wise guy answer.

I don't see the trailer and home as having the same type of water system and therefore I manage them differently. Home has essentially unlimited supply and drain capacity. It has fully chlorinated water in all the lines (the filters at the kitchen sink and fridge ice maker are at the points of use). If we've been away, I can easily flush the system and refresh every drop in the system in about 5 minutes by wasting water.

We dry camp a lot ("mostly" is probably a more accurate description). Every drop of water in the trailer is precious to us. Our supply and drain capacity are both limited. I use a Camco in line water hose filter (the blue one... replaced annually) to clean up the water (including, I believe, reducing the chlorine content), so what's on board isn't as well protected from algae growth or bacteria as is the water in my home system. When we pull out of the driveway I want the grey tank empty, the black tank flushed, treated and refilled to 10% and the fresh tank and water heater full with fresh, perfectly clean water. After all, there isn't an optional on the trailer to open the tap until the water runs clear and doesn't smell anymore.

That's why I empty all of the water between trips, purify the system often and refill just before setting out.