Will a 40 gal hot water tank be enough for 4-5 people?
#1
Will a 40 gal hot water tank be enough for 4-5 people?
My daughter, husband, and 3 small kids live in the household, she takes a shower at night, her husband in the morning, and all 3 kids take a bath and play in the tub in the early evening. I know a 40 gal hot water tank is cutting it very close with 5 people but her old 40 gal boiler mate hot water tank connected to the boiler just went. I have a spare 40 gal regular power vent hot water heater that I was going to install for her for the time being, would a regular 40 gal gas heater be enough for them until they can purchase a new 50 gal heater, it's just something they can't really afford right at the moment? I thought maybe a regular hot water heater would have a better recovery rate than the old boiler mate and maybe it should give them enough hot water that they'll need..

Top Answer
03-14-23, 12:38 PM
I grew up in a family of 8 people. We had a 40 gallon gas water heater and rarely had problems.
It may take some minor use timing adjustments but nothing major.
Gas heating recovery is very fast.
It may take some minor use timing adjustments but nothing major.
Gas heating recovery is very fast.
#2
Forum Topic Moderator
We have an electric 40 gallon water heater but it's just me and my wife. BUT any working water heater is better than no water heater. Worse case scenario is they'd have to leave a little time between showers.
#3
Member
For electric, I would say probably not, but for gas it will be marginal, but in a pinch they should be ok if they space out baths and showers, laundry, etc. You can improve the situation by running the tank at a higher temperature, but that wouldn't be safe with kids unless you install a tempering valve. You can get easy to install versions now, like this one:
https://www.lowes.com/pd/Cash-Acme-3...6981&gclsrc=ds
But of course, that adds to the cost. Another plus for them is that running the tank at higher temp (140) helps prevent legionella from thriving in the tank.
https://www.lowes.com/pd/Cash-Acme-3...6981&gclsrc=ds
But of course, that adds to the cost. Another plus for them is that running the tank at higher temp (140) helps prevent legionella from thriving in the tank.
#4
Group Moderator
It sounds like a good situation for a 40 gallon water heater to succeed. They are already spreading their use through the day. Plus, if they are aware of the limitations they can make minor adjustments like when they do laundry or wash clothes.
#5
I grew up in a family of 8 people. We had a 40 gallon gas water heater and rarely had problems.
It may take some minor use timing adjustments but nothing major.
Gas heating recovery is very fast.
It may take some minor use timing adjustments but nothing major.
Gas heating recovery is very fast.
#8

"" ... It helps if your mom is a n a....""
"" ... maybe a regular hot water heater would have a better recovery rate than the old ...""
Unknowns that need research before they can be used to influence the decision of whether to get a 50 gallon water heater. More expedient go ahead and install the 40 gallon rather than waste time puzzling over them.
The most likely point of running out of hot water is filling the tub for the kids to play in.
If the 40 gallon heater turns out to be inadequate (requires trying it out) you can add a preheater consisting of a few dozen feet of finned pipe dissected from water baseboard radiators, in the cold water line to the water heater.Mount this in an open but out of the way place on but not touching the basement wall or ceiling.
"" ... maybe a regular hot water heater would have a better recovery rate than the old ...""
Unknowns that need research before they can be used to influence the decision of whether to get a 50 gallon water heater. More expedient go ahead and install the 40 gallon rather than waste time puzzling over them.
The most likely point of running out of hot water is filling the tub for the kids to play in.
If the 40 gallon heater turns out to be inadequate (requires trying it out) you can add a preheater consisting of a few dozen feet of finned pipe dissected from water baseboard radiators, in the cold water line to the water heater.Mount this in an open but out of the way place on but not touching the basement wall or ceiling.
#9
Family of 4, the 40 gal electric HWH worked for us since the kids were young to the day they went off to college. No systemic issues that I recall, moderation and flattening the curve is all that is needed.
#10
Way back when a 30gal would've sufficed for a family of 5. Bathing once a week for the kids and maybe more often for the man depending on the kind of job the man had. No automatic washing machines and no automatic dishwashers, no hot water sink dipensers. Houses were smaller, required less heat and people learned to live in colder environment.
Things change. Today a daily shower is considered mandatory, 30-to-40-minute showers are considered standard by most young people, most people run a dishwasher daily, washing machines run as much as 3 to 4 times a week. Today a family of 3 require a 50-gal water heater.
Things change. Today a daily shower is considered mandatory, 30-to-40-minute showers are considered standard by most young people, most people run a dishwasher daily, washing machines run as much as 3 to 4 times a week. Today a family of 3 require a 50-gal water heater.
#11
Group Moderator
I'm no expert but I'll throw in my 2 cents. I grew up in a 5 person home (2 adults - 3 children) and had a 40 gal propane water heater for years. No problems that I am aware of.
#12
Today a daily shower is considered mandatory, 30-to-40-minute showers are considered standard by most young people
#13
Member
I think some of this depends on climate and the output of the burner as well as the size
Where I live, it doesn’t get that cold in the winter and and gets very warm in the summer so the 55kbtu burner on my 40 gallon “quick recovery” rheem provides essentially endless hot water in the from mid spring to mid fall.
Where I live, it doesn’t get that cold in the winter and and gets very warm in the summer so the 55kbtu burner on my 40 gallon “quick recovery” rheem provides essentially endless hot water in the from mid spring to mid fall.
#15
Group Moderator
And also, most new shower heads & faucets brag about their "per minute" limited usage. Most now are 1 gallon or less per minute.
Used to, faucets were free flow.
So, based on this, households "shouldn't" use as much water as we did back 40 years ago. And too, we took a bath back then. We didn't have a shower.
Used to, faucets were free flow.
So, based on this, households "shouldn't" use as much water as we did back 40 years ago. And too, we took a bath back then. We didn't have a shower.
#16
And also, most new shower heads & faucets brag about their "per minute" limited usage. Most now are 1 gallon or less per minute.
Used to, faucets were free flow.
So, based on this, households "shouldn't" use as much water as we did back 40 years ago. And too, we took a bath back then. We didn't have a shower.
Used to, faucets were free flow.
So, based on this, households "shouldn't" use as much water as we did back 40 years ago. And too, we took a bath back then. We didn't have a shower.
But many people remove the limiting orifice and like I said, people think 20 -30 min showers are fine, and that is on a daily basis! I'm betting they uses as much hot water as the typical bathtub of 40-50 years ago, used once or twice a week. Besides there are a lot more older homes using old plumbing vs new builds with update plumbing. It's changing but as it pertains to this point in time, I don't think the majority of people (nationwide) do nearly enough to conserve water. Automatic sprinkler systems are becoming more popular. People don't like the fact that during a drought or mid-summer, grass naturally goes dormant and turns brown. They want that green at any cost. And even bidets are now being sold with hot water options, so as not to freeze one's tisshy. Water is being diverted from lakes and resivorous (sp) faster than can be replaced and the water table is being drained continuously (think sink holes popping up more often). And last but not least, most city water treatment plants are old and at their limits. Case in point is the City of Buffalo, who has stop fluoridating water for the past 7 years due to antiquated plumbing. The city is now being sued for "...violating constitutional rights to a healthy environment".
#17
Today a daily shower is considered mandatory, 30-to-40-minute showers are considered standard by most young people
moderation
Norm201
voted this post useful.
#19
A typical 30 gallon not all-electric water heater should not run cold for any family given a half hour wait between major uses such as a shower. Twenty gallons would work for not too long showers and also typical dishwashers including a running of the bulls, er, the water at the kitchen sink to get it hot just before starting the dishwasher.
"" during a drought or mid-summer, grass naturally goes dormant and turns brown. They want that green at any cost ""
When the lawn is not kept lush and green there is the danger of getting large amounts of weeds.
"" during a drought or mid-summer, grass naturally goes dormant and turns brown. They want that green at any cost ""
When the lawn is not kept lush and green there is the danger of getting large amounts of weeds.
#20
When the lawn is not kept lush and green there is the danger of getting large amounts of weeds.
#21
Member
My 2¢ = Definitely doable.
My first suggestion would be to make certain the tank is well insulated (fiberglass heat blanket) and as much of the hot-water piping is ALSO insulated.
Technology Connections - A simple water heater is more clever than it seems
Second, it's simple to close the tub drain while taking a shower and save/reuse the water- since you're generally adding bubble bath etc for small kids, the once-used soapy water isn't a problem.
Just leaving the hot shower water in the tub helps to keep the tub pre-warmed for the little kids. FWIW, I do sorta the same thing even with our '3/4 bath' (sink, toilet, & shower stall) by putting a washcloth over the drain to hold about 1" of water to warm up the shower floor on cold morning.
Third, (and something I just learned) you can dramatically cut down on hot water usage for clothes washer. What I RECENTLY found is that you can get ALOT of clothes cleaning by simply soaking dirty laundry in cold water, then putting the cold water on "heavy load / high speed agitation" and you get a TON of dirt out of the clothes WITHOUT any soap, detergent, or hot water.
So, then you run a smaller amount of water set to on 'warm' or 'hot water' and get the same outcome.
My first suggestion would be to make certain the tank is well insulated (fiberglass heat blanket) and as much of the hot-water piping is ALSO insulated.
Technology Connections - A simple water heater is more clever than it seems
Second, it's simple to close the tub drain while taking a shower and save/reuse the water- since you're generally adding bubble bath etc for small kids, the once-used soapy water isn't a problem.
Just leaving the hot shower water in the tub helps to keep the tub pre-warmed for the little kids. FWIW, I do sorta the same thing even with our '3/4 bath' (sink, toilet, & shower stall) by putting a washcloth over the drain to hold about 1" of water to warm up the shower floor on cold morning.
Third, (and something I just learned) you can dramatically cut down on hot water usage for clothes washer. What I RECENTLY found is that you can get ALOT of clothes cleaning by simply soaking dirty laundry in cold water, then putting the cold water on "heavy load / high speed agitation" and you get a TON of dirt out of the clothes WITHOUT any soap, detergent, or hot water.
So, then you run a smaller amount of water set to on 'warm' or 'hot water' and get the same outcome.
#22
My daughter picked up a used 2 year old hot water heater just so we could get hot water back in home. In the mean time as I was getting ready to remove the boiler mate that was leaking I noticed the leak was from coming from a plastic drain valve under the tank, put a nipple in and a cap which stopped the leak. I now have that 40 gal water heater sitting in the garage which she just resold and putting the money towards the 50 gal tank that she wants. Problem is the person wants to come look at the heater and makes sure that it runs, only thing is I don't have a gas line in the garage to fire the tank up. Someone told me to just hook a BBQ propane tank to the heater just to show the person that the burning works, is that possible to do? Can you run propane through a natural gas valve just to see if the burning will ignite?
Last edited by mark249; Yesterday at 02:10 PM.
#23
It is tricky and dangerous to test a natural gas item using propane. It may or may not work with propane depending on the exact makeup of the gas burner. Also, depending on the exact makeup of the burner, propane could damage it with an internal explosion..
"" run a smaller amount of water set {the washing machine} to on 'warm' or 'hot water' and get the same outcome.""
Running a washing machine with too low a water level for the amount of clothes will tend to fray the clothes and stress the seams in the clothes' fabric. But a partial cycle or presoak without detergent is still useful for unusually soiled clothes as you described.
Also, running the water heater empty for even a few seconds while you examine the flame for proper color and gas/air mixture will damage the tank.
"" run a smaller amount of water set {the washing machine} to on 'warm' or 'hot water' and get the same outcome.""
Running a washing machine with too low a water level for the amount of clothes will tend to fray the clothes and stress the seams in the clothes' fabric. But a partial cycle or presoak without detergent is still useful for unusually soiled clothes as you described.
Also, running the water heater empty for even a few seconds while you examine the flame for proper color and gas/air mixture will damage the tank.
Last edited by AllanJ; Yesterday at 03:41 PM.
#25
Member
Originally Posted by AllanJ
Originally Posted by Hal S
run a smaller amount of water set {the washing machine} to on 'warm' or 'hot water' and get the same outcome.
I generally do the soaking set to full water level, then set the washer for the 'actual' level of clothes.
And it's not just extra-dirty clothes, even regular-level dirty laundry has a large amount of dirt removed from just motionless soaking then agitation: it's surprising how much dirt comes out through physical removal- which means less detergent because you're not wasting it on dirt that doesn't need to be removed chemically.
#26
Thanks, I'll try to get it into the basement so I can hook it up to a gas line...