hot water demands

jonny88

Has anyone been experiencing an upturn on hot water demands.For some reason my last two customers want three showers running at the same time for 20 minutes.When you start to add it up with body sprays etc its getting a little crazy.A prospective customer was told her 50 gallon water heater was good for what she needs.After explaining to her the limitations and what I proposed to her she thinks i am crazy and trying to take her money.How do you guys handle these people.

Zman

Recovery Rates

The amount of storage is really not the question. Ironically most in the industry are still focused on it.



The recovery rate is far more important.

A typical electric unit only makes about .5 gpm in most setups.

A gas fire unit might make 1-1.5 gpm

An indirect would typically be in the 1.5 to 3 gpm  range depending on the boiler.



I home that would need a 120 gal electric might run just fine on a 40 gallon indirect.



Anyone that just looks at the tank size and says it will work is clearly uninformed.

If you don't ask what type of heater, you could easily be off by a factor of 6.



The correct approach is to look at the combination of storage and heating capacity and make an informed decision.



Many of the manufactures has calculators and charts that show the relationship between the two in order to help with sizing.



BTU/Hrs / 500/ Delta T = GPM

1KW/Hr=3415 BTU/Hr



Show the customer the facts and let them make the decision. Explain that this is about math not opinions.



Carl

jonny88

could''t agree more

So the customer has steam on first floor and took a hot water loop for baseboard on 2nd floor.Every room has heating problems.They are undergoing a renovation and we are proposing a whole new heating system with indirect.I have a guy I use to do my heatloss,boiler sizing ,water sizing as I know my capabilities.I put it together but as you know there is a lot more to making a system work correctly than guessworking on sizing.

Problem is they still believe the other plumber but as you say math does not lie.Thanks for your time and advice.Have a great holiday weekend.

icesailor

50 Gallon WH's:

Everything said, I can't disagree with.

The "plumber" who told your customer that a 50 Gallon WH is OK for what you describe is either a fool or just plain doesn't know what he/she is talking about.

So many here just go nuts over Indirects and how fast they recover. If you want to get the listed recovery, you have to put a lot of NUTS (energy) into being able to make that hot water. A 150,000 BTU boiler will make one heck of a lot more hot water than a 75,000 Boiler. There's an old song that I will think of all the words later about getting there. About how some people drive a Model A Ford, some people take a jet plane, They get there faster, but the Model A gets there just the same.

Many "Heaters" are CLUELESS how much energy it takes to heat water, Take a house with a 150,000 BTU boiler, and calculate the heat loss down to 75,000 BTU's and it will HEAT the house. With all those simultaneous showers and body sprays, and you quickly discover that most of (if not ALL) of that 150,000 BTU's were going to heating water. Look at the manufacturers ratings for Indirects. If you don't install the recommended size boiler for the size of the indirect chosen, it can be way below the rated output. It simply can't be done. It is no different than the Ford F-250 HD I bought to tow a horse trailer with the 351 engine, rated to tow the maximum weight of a loaded trailer. Without the trailer, I could drive up and down hills at 70+ MPH, almost anywhere. Towing the trailer with HALF the maximum rated load for the combination, I couldn't get up even small hills without a running start to keep the RPM's and Power up. I had a 2001 GMC Top Kick 5 horse van with a 360 HP gas engine. With just ONE 1200# horse, it barely made it up hills unless it had a good running start so I didn't have to downshift. The engine in a heating system is the boiler. You MUST have enough NUTS to carry the load. I'm not the brightest bulb on the tree on The Wall, and I'm not the most experienced because of the limitations of where I lived and worked. But I doubt  that there are many who have more experience than I at resolving domestic hot water issues. What I say is from hands on experience. It CAN'T be done and CYA. If you get away with it, you're just lucky. Want an example? Two dedicated Bock 73E oil fired water heaters, fired at the rated output of 1.75 GPH, recovering 220 Gallons Per Hour, each at 100 degree rise. It worked as it did for 6 years. that's 440 gallons per hour. Commercial application. The High Limit was 160+ or whatever it would maintain. The water that was used for humans was tempered to 112 to 116degrees. I replaced the 1.75 GPH nozzles with 1.50 GPH nozzles. It IMMEDIATELY started running out of hot water. The water heaters were actually too small for the application.



You can put a 50 gallon water heater in and it will work, part of the time. Its the other part of the time that they call up and rag on your @$$ and tell their friends you are a fool.

A better solution is to use the biggest indirect or storage tank you can get away with and run hotter water in the tank. Then temper down the hotter water to a safe and usable level. Raising the tank temperature is the same as theoretically installing a bigger tank.



Sometimes, customers think it is normal to be running out of hot water. If they are already worrying about running out of hot water, you better plan well. You better explain the problems, or else let the ignorant "plumber" prove his ignorance. If it doesn't work for you, the customer might be insisting that you pay to repair it out of your own pocket.

If you insist, do what I did when I had the chance. Give them multiple choices with detailed explanations of why and the cost. From the least to the best. Let them choose. That way, it is their choice.

If you don't believe me, put a garden hose on the outlet of your water heater and turn it on slow. Time how fast it runs out of hot. Then, turn it down slower and see how long it takes to recover. Once recovered, put the hose in a 5 gallon bucket and time the flow. That's your recovery flow rate. Add up the shower heads. Can you keep up with it? Doubtful.

My 40 gallon electric (recovers way less than 18 GPH because it has 3300 Watt elements)is fine for two showers. Don't try a third.



FWIW

hot_rod

It's all a guess

until you define EXACTLY how many gpm those 3 showers can flow. There is a big difference between a 2.5 gpm shower head and a 9 gpm or more body spray. Times 3!



If the homeowner cannot tell you how many gpm they need, want, require You tell them what your proposed system is capable of supplying, and have them sign the proposal.



In some cases a large dump tank 120 gallons at 160F with a thermostatic valve is best.



Low flow requirements IF you have enough boiler HP a small indirect piped to move the boilers entire output may be enough.



Asking for three 20 minutes showers running at the same time is settting someone up for failure, don't let it be you.



Use the power (math) Luke Skywalker.

SWEI

Don't forget

that the overwhelming majority of 50-gallon gas tank heaters have net outputs under 40k.  Even the smallest of boilers will outperform when paired with an indirect.



Do the math, and don't apologize for telling the truth.  Sometimes a gas tankless water heater can be part of the solution, especially when there is a high dollar bathroom or two.  I'll go pretty far to avoid oversizing the heating plant.

hot_rod

true that

inn today's low heat load homes, the DHW load can be much larger that the heat load. The boiler needs to be sized to the largest load, regardless.



But oversizing a boiler just for DHW may lead to in-efficient short cycling during low heat loads.



I'd agree in many cases with large DHW loads and low heat loads a tankless sized to the DHW might be the best match.

Zman

Size to heating

Hot rod, I completely agree that the DHW demands can be higher than the heating load. In that case it is far better to upsize the storage rather than mess with heating efficiency. A large indirect sized to a small condensing boiler is a great match as the large heat exchanger will drag down the boiler return temps making it very efficient.Tankless units are often a good call as well.

Carl

icesailor

Ideals:

The ideals are to use boiler ODR modulation for the heating load. Then P/S piping. Modulating boilers do it with ease. IMO, just don't go nuts with trying to pick one with turn downs so low that you can't get enough nuts from the hot side of the primary boiler loop.



As far as the DHW load is concerned, it is a sliding load. From the beginning of a heating season, to the deepest, heaviest load, and into the end. Like a big "U" curve. The DHW load is every day, 24/7/365. Design a heating system for a maximum of 10 days per year or a potential 24/7/365 load.

Some people used to call me for their **** moments for help. A company had changed a small, 10 YO oil boiler in a garage apartment shop. It worked fine for 10 years. I never saw the old boiler, it was already replaced. It was replaced with a W-M WTGO-3. The old boiler was probably an equivalent to a Peerless WBV. No storage tank. It was September, no heat load. They could only get continuous warm water out of the brand new boiler/tankless. It was a good install except that the Watts 70A wasn't heat trapped and there was no flow restrictor installed. (Who installs them?) When you had the control set to 200 degree HI and 180 Operating, and the boiler was maintaining 180 degrees, turn on the DHW and it was hot, slowly going to warm. The boiler just didn't have enough NUTS to heat the boiler water with enough energy for the transfer to the DHW. Not anywhere enough for a shower. The I/O manual said to use a 2.5 GPM flow restrictor to get the rated performance from the boiler/coil. I showed the installer how closing down the cold water feed into the tankless did what the flow restrictor did, slower flow allowed more contact time for the tankless coil. He installed a flow restrictor as code requires, and the world again became a beautiful place.

Another 24/7/365 load attended to.

Where I used to live and work, I figured that there was no heating load for five months or more. But the DHW load never left.

Jack

I've seen this so many times

"why didn't they tell me what it would take to heat let me use the fixture", be it tub or showers. These type systems do very well with tankless...multiple tankless that is, depending upon flow rate.



Measure the ground water, pick the model heater and use the manuf spec on temp rise to give a hard number per fixture. Count each shower head and add the body sprays, etc to arrive at a flow rate per fixture. Compare that to the output of the tankless at that temp rise. How many will it take. the diversity factor comes into the discussion at this point. This gives a hard number that the customer can see in print and you don't have to get into recovery rates, time, etc. You can also begin to compare the systems. At this point the customer can begin building the system back to reality or can go for the whole enchilada. As well, you can then get into the boiler indirect should you choose.



To me, I think the right sized boiler for the heat loss and tankless for the high flow fixtures is the right way to go. Storing vast quantities of hot water for occasional uses is hard to justify.



Should this go multi tankless the other part of the discussion is placement of the equipment. this type of demand/customer/house is usually enormous. I think it is better to break the system up and get more local to the demand.



I had a distributor call me several years ago asking me to assist a plumber on a house in MA. This poor plumber was scared to death and asked if I would come out and help him with the hot water sizing. I met the plumber at the house. It was framed up and very impressive. I would have been perfectly happy living in this guys garage. He explained that he was having a real hard time with the owner and GC. Having been there, I understood and we walked the building and checked plans and fixture loads. The master shower was 25 gpm. Ya gotta love it! I based all the load on that shower. We are standing in the garage when the owner and GC kinda come storming into the garage. Very imposing pair! Anyway, a short conversation ensues and I explain what we had done and and what it would take to heat the hot water for the shower...5 Rinnai's. The owner throws his hands up in the air bellows, turns and storms out with the GC following dutifully behind. I turned to the plumber, who was absolutely ashen, and said, "that went well". A few minutes of discussion while standing in the garage and I noticed there was a small odd sized garage door. I asked if that was for a golf cart. The plumber responded, "No, that is for the Zamboni " I looked out and this guy was also building a full size skating rink. At that point my attitude changed. I had made the trip, I told him what he needed and he blew me off in a not very nice way, just as he had been doing to the plumber. I took the plumber in tow and found the owner and his guy. Basically at the point I told him, very directly, in so many words;), that he had built it and now he had to feed it...or be PO'd every time he got in the shower. BTW, his alternate system was going to be a 200kbtu boiler and 4 120 gal storage tanks on the second floor. I laughed. Anyway, he went with the 5 and it worked well and when his son washed his hands the 25 fpm capable system fired at about 20kbtu and there was no storage.



The worst part was they continued to ride that poor plumber and he let them. Again, having been there, I get it, but it still aggravates me that I put up with it then, but you learn. Oh well, a Labor Day tale;) Think good thoughts of the working people!

SWEI

Point of use tankless

works like magic when paired with solar (as a preheater.)  Even after several overcast days, it's unusual to see a solar tank under 80ºF.  The tankless will now deliver roughly twice the flow in winter (and rarely fire at all during summer.)

icesailor

Contractors:

I think I once worked for that contractor guy. All of his poor planning constituted am emergency on MY (and everyone else's) part. Especially when he had a Sept 15th start date, a June 15th deadline, he didn't start work until November 10th, and he, his girlfriend and their three children spent 3 months in The Grenadines, drinking rum coolers. Come April 1st, came the big push. Sometimes, you just have to wish people health, happiness and LONG distance.

The Contractor had a 60 day rule. If you sent him a bill, and it was for work in the prior month but he got the bill on the 28th of the month, he considered it received on the First, so he had 30 days to consider it. 30 days to submit it, and 30 days before he paid you(me) AFTER receiving payment which was after the first. He (legally? claimed up to 120 days, even if he submitted the bill before the first when you first submitted it, and was paid the next day. Then, he asked for a discount for prompt payment.

Sometimes, for personal entertainment in June or July, I used to go find a source of good entertainment. Which consisted of watching a fully graded and ready for sod lawn, being sodded by landscapers, who were also planting trees and bushes, while the Irrigation contractor was taking up fresh sod to run irrigation lines to water the new sod lawn and bushes, while the electrician was taking up sod and burying wire for the walkway lights. The trucks of everyone are parked all up and down the dead end road to the site, guys are walking around in their stocking feet because some floors are being sanded and others are being finished, while the painters are doing touch up, and the plumber is setting fixtures. The decorators are coming on the night boat with a 50' moving van that won't fit down the driveway and the head decorator wants running water because he won't share the Blue House with anyone else. I almost forgot. A big truck was backing down the almost finished driveway. Because the location was almost in a wetland, they had to put the Septic Tank on the edge of the driveway. The driver was good at going forward but was lacking in his back up skills, and broke through the top of the Septic Tank that was supposed to be spec'ed for driveway and parking lot use. The load of Blue Stone pavers was too much weight causing the truck to break the top of the tank and the truck to fall into the newly installed tank. They had to get a big gang of Central American Amigo's to hand unload the bluestone, and use a really big loader to get the truck out.



You can't make this stuff up. The old WW ll term FUBAR (Frigged Up Beyond All Reason) comes to mind. Or, the other old WW ll one. SNAFU. Situation Norman. All Frigged Up.



I do miss the sources of entertainment. I don't miss being part of the show.



That Contractor went through a lot of plumbers until he ended up with the most miserable MF that ever walked the face of the earth and didn't give a rats red rectum about anything. They worked well together.

icesailor

Tanks:

I never suggested using 5 -120 gallon indirect storage tanks for the 25 GPM shower.



All I was saying is that if you pick a Veissmann Vitodens 100, and think you can hook it to a 25 GPM shower system, you might want to check your math.

Jack

Ice,

I wasn't suggesting you recommended anything. I did think you would relate to the story!

icesailor

Relations:

Jack,

Did my related story cover it?

When you have to work around those kinds of people, you quickly learn that you have to wish some of them Health, Happiness and Long Distance. That they will have to "Call Someone Else" If you let your pride get in your way, your pride can cost you a lot of time, money, and uncompensated time.

jonny88

all to no avail

so I brought a heating consultant to the job.He asked all the questions regarding water usage etc.He told the homeowners the way the contractor is insulating is below par and will effect heat distribution etc.There is a steam boiler with 2 hot water zones plus a 50 gallon water heater.All first floor is getting renovated with a 600 sqft addition to first floor.Contractor wants to use existing steam rads and make a hot water zone in addition using toe kick heaters.Upstairs is wall to wall baseboard.Homeowner gets headaches as his room gets to hot before daughters room gets satisfied.Anyhow they want to run 3 showers at the same time for 20 minutes.Heating consultant wants to put in a modcon with a indirect ,I forget what size he said.He initially wanted a reverse indirect bit the boiler would have been way to big on heating side.We were going to put panel rads(jaga) with TRV's.Long story short he got thrown out by gc and told he was going to delay project.So we are going back to original design except we are putting in a 75 gallon water heater.Homeowners have asked me will it work and will the heat work.I told them they wont get what they want from hot water heater and the GC is basically guessing on the heat.No heatloss will be performed .I told homeowners I will do everything GC tells me to do but call him for heat related issues.I do like the tankless idea Jack and will talk to my heating designer.He usually goes with a reverse indirec and a storage tank.Anyhow of we go for another exciting day.

icesailor

Smart:

My old and dear friend Max, the electrician has a saying. Whenever I was in a quandary, I would seek him out as someone to throw things around with He had a long and great answer that always resolved issues like yours.

"They're smart. And We're NOT.

As another old wise doctor once said about ideas that he came up with that he bounced off someone like I did with Max the Electrician.

"That might work for you. I've never seen it work for anyone else, but it might work for you".

Think of those two things when thinking about the owner and his puppet contractor. They always want the loaded Pizza, "The Works" when they order it. When they find out the cost, they start dropping what they decide they don't need.

Zman

Tough One

Jonny88,

All you can do at this point is document that you design based on math not opinions and let the owner and builder swim in their own mess.



Speaking of math,

bc 3510, you seem to have some interesting ideas.

First off what kind of water heater has such perfect stratification that you get 85% of the water out at full temp. I have never seen one.



So recovery doesn't factor in? I have an indirect that will put out 2.8 GPM all day and never run out of water. It could be magic or maybe it is the 100kbtu boiler connected to it.



How do you think tankless heaters work?



Yes my system will run out of water eventually at 6gpm but it takes a long time.

icesailor

Stratification:

If Stratification is or becomes a real issue, the best way to resolve it is with return circulation. Especially on high output water heaters like Oil Fired or commercial high recovery gas units  that see very short intermittent draws.

With very high recovery/output heaters like Bock 73E oil fired water heaters recovering 220 gallons per hour @100 degree rise, you can have 180 degree water at the top, many different temperature layers on the way down, and 55 degree water coming in. It won't work well on undersized or under-fired tanks.

Its the concept.

jonny88

Thankyou all for your time to respond

My potential customers have come back to thinking mod/con indirect.I told them again I am having no responsibility for heating design that contractor is proposing.After spending a few hours with them we went over pros and cons.Example,functioning basement bathroom.It works and gets used once a year when owners brother comes to stay.They wanted to gut and renovate it.I suggested why not paint it ,dress it up a bit and put your money into heating system.They are coming around and if no one has any objections I might direct them to this post.Thanks again.

jonny88

interesting

I never heard of this unit and looked it up.Have you been using it long .Looks great and has a lot of answers to some potential problems.As for H stamp much respect to Gennady but where I am and what I see if inspectors actually Inspected installations we might have a better chance of advancing .Thanks for the link

jonny88

Ok

But what about Gennady said,I looked it up and it looks great,how many have you used.Is the price I saw online for real,around 6k.I am definitly going to look into it but for that price I know what I am getting with the products I normally use.Thanks again for the link.I see you work in NY who has this unit.

Rich_49

Let us

know what the final decision for equipment / strategy is for this nightmare .  If you are still thinking just water heater you can give them what they want , they just need to pay for it .  You will never want to use anything else to only heat DHW .  AO Smith Cyclones or anything with similar outputs don't even come close and it's modulating technology .

http://www.htproducts.com/phoenixwaterheater.html

   Did I mention they cost the same as those high recovery P'sOS ?  Just replaced a commercial water heater in a rehabilitation facility . Others gave price for this http://www.hotwater.com/water-heaters/commercial/water-heaters/gas/master-fit/master-fit-standard-draft/ 300K and 100 gallon , and we installed this  http://www.htproducts.com/literature/MKTLIT-52.pdf 320K and 119 gallon for the same price and the unit cost us 300.00 less than the POS . This unit only did the laundry and kitchen .

 Wait till they get the gas bill for September and it is 40+% lower than the 7,000 + they paid in July . They have 2 more that do the residential sections that are about to die plus 2 -1,333,000 BTU Iron Firemen that nobody ever maintained (what a shame) , State is about to condemn those . Probably can put together a hell of a package if we can convince owners we can do it all one time and get them from 140,000+ yearly in NG down to 65,000 or better .    

SWEI

Phoenix Plus

Had not seen those before -- interesting design.  Do they have an ASME stamp?

Rich_49

Don't believe so

being as both gas assemblies are below the 200,000 BTU range requiring ASME stamp .

http://blog.waterheaterstore.co/asme-or-non-asme-that-is-the-question/