Domestic Hot water(THANKS, It works great now)

[rombi]

I have an outdoor boiler and I have an electric hot water tank in my basement that was hooked up to the boiler for domestic hot water when the fire is going. It is just hooked up using natural convection to heat the water. It takes a long time to heat the water and this year I noticed that it gets cold after running out a couple of gallons. This morning I took a shower and about 5 minutes into it the water was luke warm on full hot. I made sure there was no air in the line last night. I don't know why this year it seems to be heating less water. I even turned up the mixing valve a little to get more hot water in the tank.
Maybe I need to put a pump on that loop to push the hot water through faster?
Any help would be great. Maybe I will take a pic of my set-up tonight and post up on here.

 

[Nofossil]

Welcome to the forum. It would be good to get a picture and a quick sketch if possible showing how it's set up. What do you have for a heat exchanger between the boiler water and the domestic hot water tank? Is it a coil in the boiler?

 

[rombi]

It was put in my uncle who is a plumber. It is a sidearm I guess. All it is just a pipe inside of another copper pipe. He made the whole thing. He has done this on a couple of other peoples hot water I guess.

 

[Eric Johnson]

Welcome to the Boiler Room, rombi. How 'bout those Packers?

If you have hard water, rombi, like my folks over in Coloma do, then there are two potential problems that can crop up with a sidearm. Either the inner tube is becoming jammed up with mineral deposits, or there is scale in the bottom of your electric water that is restricting the gravity effect. Actually, both restrict the gravity effect, but have different solutions.

If it's simply a matter of scale in the tank (I have a sidearm and it's a problem I have to watch out for), just drain 15 or 20 gallons of water out the bottom drain and it should clear it up. Then remember to drain off 5 gallons every week or so to keep the bottom of the tank clear. It doesn't take much to mess up the convection.

If you've got mineral buildup inside your sidearm, on the other hand, then it's time for surgery. You'll have to replace the inner 3/4-inch tube with a new one. Unfortunately, the only way to get that tube out of the assembly is by cutting one end off the heat exchanger (both tubes) because there's no way you're going to heat up both connections enough to pull them apart. At least, I doubt it. You can put in a new inner tube and reassemble the hx--it will just be a couple of inches shorter.

In both cases, you can prevent future problems by pumping the water instead of letting it convect through gravity. A Taco 007 piped into the DHW line will keep everything clear. I forget which way you need to pump the water--maybe it doesn't matter. I guess as long as it's going the opposite direction as the boiler water, you'll be in good shape.

So I'd try the draining thing first. If that's the problem, you should get chunks of lime coming out the drain with the water. If that doesn't work, then it's probably time for the SawZall.

Good luck and let us know how it turns out.

 

[rombi]

I will try to drain some of the water tonight when I get home. The water going to it is softened so I am not sure if there is too much build up in it. I will try to look up the pump as well and see how that works.
When my wife wants to take a bath now I just hope that the hot water will hold out, but lately I had to turn on the electric so I don't have to worry about it running out.

 

[Nofossil]

If you discover that you have hard water deposits, don't reach for the sawzall just yet. You can dissolve these deposits with white vinegar, available by the gallon in your favorite grocery store. Fill up the offending item and heat it if possible, let it sit for a few hours, slosh it around, and repeat. Drain it and be amazed. I've rejuvenated finned heat exchangers that were blobs of calcium this way.

Sawzalls belong on the shelf next to the epoxy.

 

[Eric Johnson]

And my favorite tool is a vice grips.

Worth a shot, nofossil. I'm trying to figure out how you could do it without removing the hx (more sawzall action). If it can be isolated from the tank, it might be possible to pour the vinegar into the inner tube through the bleeder hole, or up through the drain, if it's piped right.

 

[Nofossil]

All depends on how it's plumbed in. Might still be easier to cut it out than to cut it apart. I'm not at all above quick and simple - I advise the vinegar because I'm lazy and it sounds too much like work to do otherwise.

I have at least six different configurations of vise grips. Have you tried the new automatically adjusting ones? You set the clamping force rather than the clamping distance. Very different to use, but I think they're an improvement. Big admission here - I have a sawzall and epoxy, too. And you make a better solder joint than I do.

 

[Eric Johnson]

Do you have any German ancestors, nofossil? My dad worked with a German engineer overseas once. The Germans call a Crescent wrench an "Englander," implying that only unsophisticated Brits would use something as crude as an adjustable wrench to turn a nut or bolt.

I'll have to try a pair of those vice grips. Sounds like a pretty neat variation on a tried and true design.

 

[rombi]

When I drain out the bottom of the water heater and there is deposits in it am I going to see anything in the water?

 

[Eric Johnson]

If it's like mine, when you run the water through your fingers, you'll get little clumps of minerals in your fingers.

You'll know if it worked a few minutes after you turn off the tap. The top pipe should get really hot, as the water begins to move again. If not (assuming the boiler is up to temp), then you might have to consider Plan B. I don't know if there's a good way to test for a hard mineral buildup in the inner pipe, other than observing that the sidearm isn't working. I'll think about it and let you know if I think of something.

 

[Nofossil]

Do you have any German ancestors, nofossil? My dad worked with a German engineer overseas once. The Germans call a Crescent wrench an "Englander," implying that only unsophisticated Brits would use something as crude as an adjustable wrench to turn a nut or bolt.

I'm 1/4 German and 1/4 English - no wonder I'm messed up. The other half is Scotch, so I'll just have a glass of single malt when the internal conflict gets to be too much.

 

[pdboilermaker]

While softened water will reduce the amount of minerals in the water, it will not eliminate it totally. This isnt to mention that rust is a typical issue with tank type water heaters. And, some how, water when heated will put hardwater stains all over the place, look at a coffee pot vs a cold water pitcher in the fridge.

But, now for the big question - Did you fill your OWB with water from the hose? If yes, then this may be your issue. Outside water is typically not connected to the water softener so you filled your OWB with hard water. If this is the case, you probably have a build up in your sidearm.

If you filled it with soft water, how many gallons does your OWB hold? How many gallons of soft water do you get / generation cycle? Is it possible that you over ran the alloted amount of softwater and filled your OWB with 1/2 soft water and 1/2 hard water? If so, then agin look at your side arm for the mineral deposites.

 

[rombi]

I bought some pre-mixed antifreeze when I filled it. It is a closed loop system/

 

[Eric Johnson]

English, Danish and German here. That's all the excuse I need to drink good scotch when I can get my hands on it.

I'm really glad you brought this up, rombi, and I hope we can solve your problem without too much disruption. I really think it's probably sediment in the bottom of the tank. Here's why:

I've been running a gravity-feed sidearm on my system for going on 4 years. The first two, the hx was connected to a gas-fired water heater, which I turned off in the winter when the wood boiler was going. I never had a problem with mineral deposits building up or with sediment in the bottom of the tank, at least not to the extent that it affected the sidearm.

Late last winter, however, my gas heater died and I decided to replace it with an electric tank, since I was planning on getting my new boiler and don't intend to use gas or electricity to heat hot water from now on. So I opted for a cheaper storage tank, basically.

But that's when my problems started with the convection. I quickly learned that periodically draining it off was the solution.

Over the summer I decided to build a new sidearm with a 1 1/2-inch copper outside tube, basically because I had the parts laying around and it seemed like to good way to kick off my new project. So I took the old (1 1/4-inch) model out. I expected to see mineral buildup on the inside tube, but other than the black film you get from boiler water, it was clean as a whistle. I was hoping that the new sidearm would not have the same sediment problem, but, as I was somewhat rudely reminded one morning when my wife ran out of hot water mid-shower, problems left unaddressed don't usually solve themselves. We have a pretty good water softener, too.

I think the responsible thing would be to pipe a 007 into the DHW line and be done with it, but I like the idea of natural convection, and am therefore willing to put up with the minor hassle and relatively minor waste involved in draining off a few gallons every week or so.

Anyway, I don't know why an idle electric tank would act differently than an idle gas tank where mineral sediment is concerned, but sometimes you have to just recognize the obstacles and figure out the best way around them.

Good luck, and let us know how it turns out.

 

[rombi]

OK I just drained 20 gallons out of the bottom. At the very beggining there was about 6 oz of darker water then it was very clear. The 20 gallons were all about 60 degrees. I do not know too much about hw tanks but shouldn't it have started to get warm out of the bottom? Anyway I will run the tub now and see if it maintains the temp. It is like a 60 some gallon unplugged electric if that matters. Thanks for the info guys when this thing works it saves us almost 50 bucks on the electric bill.

 

[Eric Johnson]

It won't be warm if the hx isn't working and the power is turned off.

The true test will be if you get any hot water, but that takes awhile. If you put your hand on the top, 3/4-inch pipe, it will be hot if the thing is working. The bottom pipe will stay cool for hours, so don't worry about that.

Also, I assume you have a bleeder at the top of the hx on the DHW pipe, and that you've bled any air out. An air pocket up there will have the same effect as crud on the bottom pipe = no convection, no matter what.

 

[BrownianHeatingTech]

Is the cold inlet through the bottom or top of the tank?

If it's through the top, the dip tube may have fallen out, allowing cold water to take a "short cut" across the top of the tank, over to the hot outlet.

Joe

 

[jklingel]

FWIW: Once you get your crud problem solved, go ahead and install a pump on your tank. I have been using a pump on a timer (15 minute minimum) for years, and have it pump 3x/day. Just two folks in the house now. It works well, though if we have an unusually heavy day, my wife will pull a few more pins on the timer and get a couple more 15-minute runs in. I don't know if we've ever needed that, but she frets about running out of hot water. Funny thing is, she's always telling me to go take a cold shower.... Good luck w/ your problemo.

 

[rombi]

Well seeing as though I hate wasting hot water I did not try to fill the tub last night. This morning I had a very hot shower which I did not have the previous morning. The 3/4" pipe at the top became very warm a few minutes after I drained the tank last night. I think I may add the pump because if it saves me from hearing, "Tom, we don't have hot water" calling down from upstairs while my wife is trying to give our daughter a bath it will be worth the cost. How much do those pumps cost? I think someone said it was 007 Taco pump right? Sorry it was the guy with the avatar with the big tree getting cut.
I think that draining the tank did help though.
Thanks guys I will keep you posted if it makes it while filling up the tub.

 

[atlarge54]

Well seeing as though I hate wasting hot water I did not try to fill the tub last night. This morning I had a very hot shower which I did not have the previous morning. The 3/4" pipe at the top became very warm a few minutes after I drained the tank last night. I think I may add the pump because if it saves me from hearing, "Tom, we don't have hot water" calling down from upstairs while my wife is trying to give our daughter a bath it will be worth the cost. How much do those pumps cost? I think someone said it was 007 Taco pump right? Sorry it was the guy with the avatar with the big tree getting cut.
I think that draining the tank did help though.
Thanks guys I will keep you posted if it makes it while filling up the tub.

A Taco 007 used to be about $65 or so locally really common on ebay it's about bottom rung as circulators go and to my line of thinking would be almost too powerful for the siphon loop of a sidearm. When you think about wasting hot water the top load washing machine is just about king of the hill. Another thought about the pump, you might lose the stratification effect when drawing down the tank and lose some temp at the tap? This is my first attempt at using the quote feature so I don't know how it'll turn out. I can't remember if flanges were included in price I think they're extra.

 

[BrownianHeatingTech]

You want a Taco 006 for that application. But it needs to be a bronze pump, not the typical iron. Iron pumps will rust out when exposed to domestic water continuously. The fresh water has dissolved oxygen, and continuous exposure to that is bad for iron pumps. They do okay in closed heating systems, because the initial load of oxygen dissipates quickly, and then there is no more. But on domestic water, the exposure is non-stop.

A 006B should be $150 or so, depending on where you buy it. Some of them have built-in check valves, which is not something you need or want. Some have threaded connections, and others have sweat connections. Doesn't matter which you get, since you will never need to remove the pump body from the pipe... if the pump ever fails, the motor and internal cartridge are replaceable without disconnecting the pump body.

If you can't find one for less than that, let me know and I'll sell you one, but I expect that ebay or something may net you a better deal than that...

Joe

 

[rombi]

OK well draining seemed to work. I wish I could help people out as much as I have been helped. I know what I know and plumbing is not one of those things that I know.

 

[pbvermont]

"Well draining?" I'm not sure you want to use this phrase. Careful. Others of limited plumbing knowledge read these posts.

 

[rombi]

"Well draining?" I'm not sure you want to use this phrase. Careful. Others of limited plumbing knowledge read these posts.

Meant to say that draing the bottom of the tank worked, fingers and mind were not working the same.