Whats the best way to heat domestic hot water

[Hard Bark]

I see diff. ways, some have a side shell and tube hx (connect top and bottom of hot water heater) and I also see plate and frame connect to the cold supply to the hot water heater. Just wondering what better???????????

[JSNH]

I like the sidearm or an indirect tank with a coil. With the sidearm you need a temp. regulator on the hot out. The sidearm is retrofitted to a gas or electric hot water tank so you have summer back up but you also have the usual short life on those tanks. The indirect tank a thermostat turns on the heat to the coil. Either way the water is hot and at the same temp.The plate you have a greater chance of the temp wandering.

JSNH

[upsnake]

If you use a lot of water and you want to go all out. Put a plate hx in prewater heater. Then put a sidearm in, you will have unlimited at water at that point.

My setup is going to be half of that, I am putting the plate hx inline before the water heater but no sidearm. So all my water heater has to do is maintain the water temp, it will be preheated coming in.

[Holmes]

I am assuming this is for your outside boiler. If you have an existing electric or gas water heater you should use the tube hx piped to your outside boiler. If you are buying a water heater I would suggest an indirect water heater with a heat exchanger built into it.  A stainless steel unit 60 to 80 gallons should be plenty large enough and should have a lifetime warranty but they are expensive.  Holmes

[Hard Bark]

Sorry, I should have said(for an outdoor wood burner) Thanks for the info.

[thecfarm]

If you are even thinking about heating your water with a OWB in the summer put some valves in so you don't heat up the house loop too.

[doctorb]

I would like to not run my OWB in the summer just for hot water.  I would also like to know if there is any good alternative to using my oil furnace to heat the DHW during these warmer months.  It seems wasteful to keep the furnace temps up constantly, when DHW is not constantly called for.

This is especially true in the second of my 2 basements, which only provides DHW to one powder room and 2 full baths (No laundry, no kitchen, no dishwasher).  So I burn some oil in the summer just waiting for one of my daughters to take a shower.

Are there any other methods that can provide a steady stream of hot water (girls take long showers), be cost effective, not lower shower water pressure, and provide hot water on demand rather than keeping it hot with oil 24/7?  Would a small electric heater be better?  Your thoughts and suggestions.  Thanks

[ely]

imo, it would be cheaper in the long run to re-educate the daughter on how to properly take a shower.
we have a 13 year old boy who thinks long showers are the way it is done, i hate to tell him but , i have installed a valve on the hot water tank in the new house, he will have x amount of time to get the shower and get out.

i am certain he thinks i am just kidding, much the same way i thought my dad was kidding when i was that age... cold water is a great teacher.

[doctorb]

Good idea, but my wife would kill me!

[beenthere]

dr
As a boy, before drawing water for a bath I had to go to the basement and build a fire in a small wood burner that heated the water in a tank. That was our DHW.  Put one in for the daughter, and if the fire wasn't good enough, the shower will be shorter.  For a longer fire, another trip to the basement to put more wood in to burn.   Yup, I know that really won't work.

Our daughters learned that a looonng shower would somehow cause a spurge of cold water coming from the shower head. Just a momentary closing off a hotwater valve in the basement can be a great wakeup call when they fall near asleep under the shower head.

[darnet]

Hey Doc,
  The way mine is set up is a loop after the hex (header). The zone circulators and the dhw draw all demands from this loop. I have a hot water tank 40gal with a coil inside. Never run out of hot water. If for some reason your demand is really great the furnace backup kicks in to help but mine don't run at all.

[doctorb]

Hey- I am not a plumber (urologist! - sorry - medical joke :D) so let me get this straight.  You have a loop in your hot water line from your oil burner to a 40 gallon tank.  This tank is a passive hot water storage tank, so when hot water is demanded it comes from there first?  When you start to drain the hot water from the tank, it fills with hot water heated in the jacket of your furnace?  Doesn't your furnace have to keep the jacket up to temp 24/7 and therefore have to run intermittantly, regardless of the hot water draw?  Help!

[darnet]

The loop is part of the header that the circulators work from. The dhw is a zone just like a heating zone. When it calls to heat your dhw a circulator kicks on to run hot water thru your hot water tank to heat the water. when the demand is to great or your owbs temps are low or not running as in the summer the furnace kicks on to take up the slack.

[darnet]

Sorry I didn't answer your other question. Yes it does have to run once in awhile to keep temps up but its not very often with todays tanks. If you don't like that idea for summer use you can install a tankless dhw heater but I didn't go that route. When I upgraded my heating system from steam to hot water heat I also put a new condencing gas furnace and a new dhw tank along with the owb.
  Scott

[submarinesailor]

If you are trying to lower your hot water cost without buying a new H/W heater, I would perform the following:

•  Reduce your hot water use
•  Lower your water heating temperature - some say 105-110.  I still like HOT water on my lower back, so I lowered ours to 115 from 120.  NOTE - We were always taught by the military doctor's in training that the skin begins to burn at 120, some fair skin people burn at lower temperatures - doctorb correct me if I got it wrong.
•  Insulate your water heater tank
•  Insulate hot water pipes
•  Install heat traps on a water heater tank
•  Install a timer and use off-peak power for an electric water heater
•  Install a drain-water heat recovery system.

If you are going to replace/install a new one and have access to natural gas, then I would look into one of the BETTER QUALITY tankless heaters.  But, if you are total electric or propane, I would consider a tanked heater and insulate it with one of those tank insulating kits you can get at one of the big box stores----------plus all the other items listed above.  One more thing on the electric type - put a timer on it as stated above.  There is no need to run it from midnight to about an hour before you get up in the morning.  Plus what about the middle of the day?  If no one is home for several hours, click it off.  I have used them in 2 separate houses and found that they work.  Also, if there was no chance of freezing, we always turned it off while we were gone for several days or more.

Bruce

[darnet]

I was going to add some pic but can't seem to do it right but they are on the site if you want to look at them.
 Scott

[beenthere]

darnet
You are so close with your pics, just as well move them into your posts.

Have the gallery open in a window, and click on your pic. Then scroll down to see where moving it to your post is done. Two ways to do it.
Click on Preview before posting to see that what you want is actually in your post. It is easy, now that getting the pics in your gallery is done.

Interesting set of pipes you have. A church pipe organ comes to mind.

[doctorb]

Bruce-

That's the kind of info I'm looking for.  I have 2 basements with two furnaces, each of which supplies DHW to a portion of my house.  Crazy, I know.  It's an old log cabin add-on farmhouse-addition type thing.  Cool but wierd.

Anyway, currently I have to keep my oil furnace on in both basements to supply everybody with hot water on demand during the non-OWB months.  So do I.....

1.  Shut down the lesser half of the house's DHW and make the girls shower in our bathroom.  They're now 17 and 20 years old and aren't interested in that anymore.

2. Get electric hot water heaters for use when I am not burning wood, one for each basement.

3.  Get DHW on demand through a tankless system in the "old basement", supplies only two full baths as above.  I have propane available, but would have to run another line, as well as electric.

I don't see how the passive tank helps me that much, as the furnace is set to hold a temp of at least 160 degrees throughout the day, regardless of DHW use or not.  So those are my unusual variables.  Any other suggestions for "summer" DHW?  Doctorb

[Holmes]

Doctorb  it sounds like you have a boiler with a tankless water  heater. The easiest thing to do is turn the electric switch off to the boiler when hot water is not needed. Or have an electrician put in a couple of timers , set the clocks for boiler operation say for 4 am to 8 am and let the family know this is the time we will have hot water, or set it so you get hot water 2 times a day.  It is like having a clock thermostat for the boiler but it needs to shut the power OFF to the boiler a clock T stat will not do that.   Holmes     " I used to be a brain surgeon  then I found out plumbers make more money so I switched "  ;) ;D ;D 8)

[doctorb]

Thanks - and I know I am not smart enough to be a plumber.  The timer sounds like a good idea.  I wonder how much oil you use with a "cold start" a couple of times a day versus the oil required to keep the water jacket of the furnace warm 24/7?

This solution will certainly work on the furnace for the bathrooms only.  However, the other furnace services the laundry and the kitchen as well as one bathroom, so I don't see a way to use a timer there.  We seem to to laundry at all hours of the day!

[Holmes]

  I wonder how much oil you use with a "cold start" a couple of times a day versus the oil required to keep the water jacket of the furnace warm 24/7?

You could save 50% per day. It may only be 1/2 to 1 gallon but for 60 to 120 days it will add up.  You can put a timer on the 2nd boiler and set it to not run at night time only.  Holmes

[doctorb]

Good suggestions on which I need to act, as the OWB heating season here is only going to last another 6-8 weeks.  Thanks, Holmes, I do appreciate your input.   Docotrb

[ken999]

Doc- Are you plumbed directly into your oil boilers or do you have heat exchangers?

I burn my 2300 once a day, all summer long, and it has enough stored btu's in the 450 gallons of water to do our domestic for 24 hours. Our 2300 is plumbed directly into the water jacket of our indoor boiler, and that has a 37 gal domestic tank on it, heated by the water from the 2300.

[doctorb]

ken999-

I have heat exchangers, in fact, I have a complete set (HWB and DHW) in 2 different basements for two separate systems. 

Your set up is interesting, and after the winter, it would not seem like a lot of work to keep it running once a day.  But my hot water is heated two ways with my system, by my understanding.  It gets heat from the heat exchanger loop for the DHW from the OWB, and its also heated in the DHW boiler jacket by the standard boiler jacket used for HWB.  without being directly plumbed to the DHW jacket, I am not sure that I have that option.

Thanks for your input.  Doctorb

[John Mc]

Doc -

Have you considered Solar Hot Water? There are some decent systems out there where they use a couple solar hot water panels to preheat a holding tank. On sunny days, this preheat tank is hotter than your main hot water tank. Even when partially sunny here in VT in the winter, it will preheat your water at least partway, so you are not refilling your hot water tank from 50˚ water from the well. You keep whatever is heating your domestic hot water now, but it only kicks on when there is not enough sun to stay ahead of your usage.

Plumbing is very simple. You just break into the cold water feed line to your hot water system and feed from the preheat tank. If you have a south-facing roof with decent sun exposure, you can mount the panels on it. Alternatively, you can mount them on a rack near the ground.

There are a number of companies selling pre-packaged systems that are fairly easy to install. Lots of folks "do it yourself", but if you are not comfortable with that, the prepackaged nature of the system makes it a snap for any plumber to hook up the system.

Here's the link to a supplier of prepackaged systems near me that ships nationwide: http://www.gosunward.com   One of the options I really like is a "timber-frame" like ground mounting rack that can easily by finished into a playhouse, tool shed, chicken coop, etc. I'm debating between that and mounting on the roof of my garage.

Their systems is eligible for a 30% federal tax credit (that's a CREDIT, not just an income deduction). Many states also offer incentives for these renewable energy systems. I'm not sure if MD does or not.

John Mc