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How much HOT WATER is enough?

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thistlescott

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Hello All,
We are still renovating and are wondering just how big a Hot water tank we need. We have a cottage that will contain three guest rooms. Each will have a two person soaker tub.
Should we plan for enough hot water to fill all three tubs simultaneously? That would require about a 120gal tank. From my research I am not sure if even the largest tankless water heater will support that. Are point of use tankless tanks enough for 1 tub and 1 sink? Can I connect two conventional or tankless tanks in series or parallel?
Any insight would be appreciated!
Thanks!
 

Breakfast Diva

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It takes a huge amount of hot water. We have 3 double whirlpool tubs and a single whirlpool tub. It depends on how many gallons your tubs are, but we were told a few years ago that the tankless WH could not keep up with the volume we need. Yes, you MUST plan that all the tubs will be used at the same time. Often when couples come home after dinner I will hear all the tubs being filled and used at the same time. I can hear the different sounds from the pipes in my kitchen.
For 2 big tubs and our kitchen, we have three 50 gallon hot water heaters connected together and it takes care of everything. When we bought our place, they only had 2 connected together and it just wasn't enough. Also, we have the temps on the heaters turned up pretty high so that cuts down on the volume of hot water needed. One of our big tubs is in a separate cottage and we have two 50 gallon tanks connected together. Our single tub room has it's own 50 gal tank.
One thing you also have to remember is that even though they are double tubs, not every couple will take their bath together. One person will take a tub bath and then the other will take a shower right after. Another thing they do is to take the tub bath, then a shower afterward to wash hair and rinse off.
We're fortunate that we live in the country and pump our own water, so we don't have the expense of having to pay for municipal water, but it does take a lot of money to heat all that water!
 

InnBloom

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I won't be able to respond about capacity because I just don't know. Sorry. But in terms of tankless, just an observation. We don't have that for the inn, but we do for our separate owners quarters, and I can tell you, it takes FOREVER to get hot water out of it. Longer than you'd expect in the summer, and a real long time in the winter. So sure, we have pipes going a long way ...it's a long story...but be aware that tankless doesn't mean INSTANT. Perhaps you already know that. We didn't.
 

Highlands John

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Would a combi boiler not be a better solution than a hot water tank?
 

thistlescott

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It takes a huge amount of hot water. We have 3 double whirlpool tubs and a single whirlpool tub. It depends on how many gallons your tubs are, but we were told a few years ago that the tankless WH could not keep up with the volume we need. Yes, you MUST plan that all the tubs will be used at the same time. Often when couples come home after dinner I will hear all the tubs being filled and used at the same time. I can hear the different sounds from the pipes in my kitchen.
For 2 big tubs and our kitchen, we have three 50 gallon hot water heaters connected together and it takes care of everything. When we bought our place, they only had 2 connected together and it just wasn't enough. Also, we have the temps on the heaters turned up pretty high so that cuts down on the volume of hot water needed. One of our big tubs is in a separate cottage and we have two 50 gallon tanks connected together. Our single tub room has it's own 50 gal tank.
One thing you also have to remember is that even though they are double tubs, not every couple will take their bath together. One person will take a tub bath and then the other will take a shower right after. Another thing they do is to take the tub bath, then a shower afterward to wash hair and rinse off.
We're fortunate that we live in the country and pump our own water, so we don't have the expense of having to pay for municipal water, but it does take a lot of money to heat all that water!.
Thanks BD,
When you say they are connected together do you mean tank 1 is connected to tank 2 and tank 2 is connected to the main supply to the house?
Or are both tanks connected directly to the main supply?
Regards
 

Highlands John

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Would a combi boiler not be a better solution than a hot water tank?.
Hey Highlands,
Can you tell me more about a combi boiler? Like what it is ;-)
.
It's basically a boiler that heats water as it flows through it, so no hot water is stored it is just heated up as required.
My sister has one and swears by it, you may need a larger one to cope with 3 baths at the same time.
 

Breakfast Diva

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It takes a huge amount of hot water. We have 3 double whirlpool tubs and a single whirlpool tub. It depends on how many gallons your tubs are, but we were told a few years ago that the tankless WH could not keep up with the volume we need. Yes, you MUST plan that all the tubs will be used at the same time. Often when couples come home after dinner I will hear all the tubs being filled and used at the same time. I can hear the different sounds from the pipes in my kitchen.
For 2 big tubs and our kitchen, we have three 50 gallon hot water heaters connected together and it takes care of everything. When we bought our place, they only had 2 connected together and it just wasn't enough. Also, we have the temps on the heaters turned up pretty high so that cuts down on the volume of hot water needed. One of our big tubs is in a separate cottage and we have two 50 gallon tanks connected together. Our single tub room has it's own 50 gal tank.
One thing you also have to remember is that even though they are double tubs, not every couple will take their bath together. One person will take a tub bath and then the other will take a shower right after. Another thing they do is to take the tub bath, then a shower afterward to wash hair and rinse off.
We're fortunate that we live in the country and pump our own water, so we don't have the expense of having to pay for municipal water, but it does take a lot of money to heat all that water!.
Thanks BD,
When you say they are connected together do you mean tank 1 is connected to tank 2 and tank 2 is connected to the main supply to the house?
Or are both tanks connected directly to the main supply?
Regards
.
thistlescott said:
Thanks BD,
When you say they are connected together do you mean tank 1 is connected to tank 2 and tank 2 is connected to the main supply to the house?
Or are both tanks connected directly to the main supply?
Regards
In our case, tank 1 is connected to tank 2 & tank 2 is connected to tank 3. That makes 150 gallons of hot water at their disposal for for 2 rooms with huge tubs, our kitchen and laundry.
In our separate cottage, tank 1 is connected to tank 2, then into the house. There is no way a single tank would be adequate for the tub in there.
We have a house we bought last year for future retirement (yeah, right!) and it has a big double soaking tub in the upstairs master bath. I can't use that big tub because the 55 gallon hot water tank is so far away from the tub and there's not enough hot water to fill it. We won't fix it until we move there permanently some day, but it sure is frustrating!!
 

Breakfast Diva

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Would a combi boiler not be a better solution than a hot water tank?.
Hey Highlands,
Can you tell me more about a combi boiler? Like what it is ;-)
.
It's basically a boiler that heats water as it flows through it, so no hot water is stored it is just heated up as required.
My sister has one and swears by it, you may need a larger one to cope with 3 baths at the same time.
.
Highlands John said:
It's basically a boiler that heats water as it flows through it, so no hot water is stored it is just heated up as required.
My sister has one and swears by it, you may need a larger one to cope with 3 baths at the same time.
sounds like what we call a tankless water heater.
 

Joey Camb

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the only trouble with a combi or tankless is that you would probably need 3 for the capacity needed. All our showers are electric which means they heat their own water so it takes the strain off the tank. we have a wacking big tank though and we only have one bath! Trouble is is for example what happened the other day DH ran two washing machines at the same time plus 2 people had showers in room 9 which runs off the tank which meant no hot water would come out of the taps in the bedrooms. What you also have to watch is people keep trying the taps which makes the problem worce so if you do run out of hot water tell them all to not use the taps for half an hour minimum.
 

white pine

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We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water.
 

Arks

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We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water..
white pine said:
...if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water.
All I know about the on-demand (tankless) hot water heaters is what I see on This Old House. That's all they install anymore, and they're in the Boston area where the ground freezes pretty deep.
Maybe it's a matter of getting the right brand, or of getting one large enough to do the job. Surely there's a way to get them to work properly.
 

egoodell

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We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water..
white pine said:
We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water.
They have been used in Europe for years where they have VERY cold winters. I will be using them in my addition and I'm on a well. I think you have to be sure that your area has a company that understands them, has been trained in them and can maintain them. We have that service here now.
Riki
 

EmptyNest

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We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water..
white pine said:
...if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water.
All I know about the on-demand (tankless) hot water heaters is what I see on This Old House. That's all they install anymore, and they're in the Boston area where the ground freezes pretty deep.
Maybe it's a matter of getting the right brand, or of getting one large enough to do the job. Surely there's a way to get them to work properly.
.
Tankless water heaters have nothing to do with how deep a well you have or how cold it gets. It is not geothermal heat. The heat is generated in the tank as it is needed. They say you never run out of it. We are considering one when our current one needs replacing. No more of those stinky rods inside that sometimes smell like rotten eggs if you have that kind of water and they often need replacing. So far we have not had that problem in VA but we did in OH.
 

Don Draper

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A historic property just underwent major renovations here to open as a b&b. They installed the tankless or "on demand" water heaters and that is ALL you hear about from their guests...people paying close to $200/night for a room do NOT want to wait 30 seconds, let alone up to 10 minutes for hot water.
They seem like a good practical solution for homes...you don't mind waiting for the hot water because you know how much money you're saving not having to fill a 40 gallon tank. Guests don't get this and frankly don't care, they just know there wasn't hot water when they wanted it.
 

Arks

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We have two 80 gallon tanks hooked up in line, also a recirculating pump so that the hot water requires no waiting. Also have separate unit for laundry, and yet another in the kitchen. One problem with tankless that we found was that if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water..
white pine said:
...if you are on a well with COLD groundwater, they may not be able to raise the temperature adequately. The instructions state that they will raise the temp x degrees, in our case it would have made only very warm water.
All I know about the on-demand (tankless) hot water heaters is what I see on This Old House. That's all they install anymore, and they're in the Boston area where the ground freezes pretty deep.
Maybe it's a matter of getting the right brand, or of getting one large enough to do the job. Surely there's a way to get them to work properly.
.
Tankless water heaters have nothing to do with how deep a well you have or how cold it gets. It is not geothermal heat. The heat is generated in the tank as it is needed. They say you never run out of it. We are considering one when our current one needs replacing. No more of those stinky rods inside that sometimes smell like rotten eggs if you have that kind of water and they often need replacing. So far we have not had that problem in VA but we did in OH.
.
catlady said:
It is not geothermal heat.
I don't think they're meaning it's geothermal. They are referring to the temperature of the incoming water.
The water passes through the heater at a given speed (the rate at which it comes out of the tap at the other end). It goes into the heater cold and comes out the other side hot. During the time it's passing through it gets heated by the walls of the heater (a coil of pipe called a heat exchanger).
If the water is too cold as it comes into the heater, it doesn't have time to warm enough before it comes out the other end of the heater.
The solution is to have the water spend more time in the heater before it comes out the other end, by passing through a longer coil, or it has to pass through a hotter coil.
 

JBloggs

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CL remember the inn not far from us where the husband died in a car accident a couple years ago? I went over to meet them one day and she explained to me in their situation they had to remove the "on the demand/tankless hot water" it had something to do with the iron in the water here. Of course I can't recall right now, but maybe the sediment was not given a chance to settle and to be filtered or something, so they had major problems with them.
Sorry to not be more specific, but I remember her telling me for them on a well in this area it was a nightmare. Since then I have heard others removing them, as we planned on building with those and a ground source heat pump.
 

Arks

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It's sounds like the secret to having plenty of hot water is to "daisy chain" several units together in a series so they're all helping each other out. As far as an answer to the question "how much is enough" I guess there is no formula like "if you have X rooms, you need Y gallons capacity". It depends on how many tubs you have and a lot more.
Maybe the best way to go about it is to put in the capacity you think you'll need, but have room to add another heater or two beside the ones you have, in case you need more later. You'll need adequate electrical or gas supply to that area for future expansion, too.
I liked the quote below that I saved a few days ago. I can't remember who said it, though:
[COLOR= #002060]Could also advise a combination of electric and tankless heat. We have one 50-gallon water heater to serve six full baths, a jetted tub, three lavs and three dishwashers. We have not run out of hot water yet. Secret is that the cold inlet to the tank is supplied by a 200,000 btu/hr tankless. The 50-gallon only serves circulation and as a buffer for short over loads when tankless output temp drops due to demand.[/COLOR]
[COLOR= #002060]When occupancy is low, I turn off the tankless preheater.[/COLOR]
 

EmptyNest

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CL remember the inn not far from us where the husband died in a car accident a couple years ago? I went over to meet them one day and she explained to me in their situation they had to remove the "on the demand/tankless hot water" it had something to do with the iron in the water here. Of course I can't recall right now, but maybe the sediment was not given a chance to settle and to be filtered or something, so they had major problems with them.
Sorry to not be more specific, but I remember her telling me for them on a well in this area it was a nightmare. Since then I have heard others removing them, as we planned on building with those and a ground source heat pump..
Yes I know who you mean. OUr water is wonderful we don't have any problems with it. I made my DH put in a water softener because I got used to one in OH...but if ours runs out of salt sometimes....I can't even tell the difference until he tells me...he refilled it and asks if I noticed anything different.
 

EmptyNest

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A historic property just underwent major renovations here to open as a b&b. They installed the tankless or "on demand" water heaters and that is ALL you hear about from their guests...people paying close to $200/night for a room do NOT want to wait 30 seconds, let alone up to 10 minutes for hot water.
They seem like a good practical solution for homes...you don't mind waiting for the hot water because you know how much money you're saving not having to fill a 40 gallon tank. Guests don't get this and frankly don't care, they just know there wasn't hot water when they wanted it..
I think it depends on how many rooms you have. I know places who use them..but they have one in each guest bath. That's a big expense at least on initial start up. Maybe if they become more popular the prices will come down...just like other things.
 
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