Author Topic: How many water heaters for 8plex?  (Read 3867 times)

srob

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How many water heaters for 8plex?
« on: October 17, 2016, 11:11:28 AM »
Hi everyone!

 I have an 8 plex housing 16 adults plus one infant. It currently has 4 standard natural gas water heaters...all of them pretty old. The oldest (about 20 years old) started leaking recently. I am going to get it removed, but I was wondering if maybe I should just take it out and leave three in place. They are all piped in series. I have never had a tenant complain about not having enough hot water.

Anyone have any thoughts on this? I am just trying to do what is most efficient...natural gas prices are low so it will probably not make much difference in monthly cost.

Thanks!

Cwadda

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Re: How many water heaters for 8plex?
« Reply #1 on: October 17, 2016, 11:16:36 AM »
Do some shopping around and see what types of units would best be suited for your complex.

If you were to buy 16 water heats you would be able to write off the taxes for all of them this year.

CareCPA

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Re: How many water heaters for 8plex?
« Reply #2 on: October 17, 2016, 11:30:41 AM »
Do some shopping around and see what types of units would best be suited for your complex.

If you were to buy 16 water heats you would be able to write off the taxes for all of them this year.

How would you expense 16 water heaters?
http://www.kbkg.com/nationwide/brochures/KBKG-repairs-decision-tree.pdf

srob

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Re: How many water heaters for 8plex?
« Reply #3 on: October 17, 2016, 11:50:23 AM »
Thanks guys.

Just to clarify, I am wondering if the three water heaters that are left in place will make enough hot water for the whole building. There is only space for four in the basement utility area btw.

CareCPA

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Re: How many water heaters for 8plex?
« Reply #4 on: October 17, 2016, 12:05:28 PM »
Sorry, I get off topic.

I would say it depends on the capacity and recover-rate of the three remaining ones, plus the water usage of the individuals. These could range wildly depending on the families.

waltworks

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Re: How many water heaters for 8plex?
« Reply #5 on: October 17, 2016, 12:07:27 PM »
You are going to put the remaining 3 (also old, right) under a higher load. I'd expect a cascade of failures at some point, which might be really expensive (not to mention upset your tenants).

IMO (and this is just me) replace it with a new unit.

-W

srob

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Re: How many water heaters for 8plex?
« Reply #6 on: October 17, 2016, 01:21:26 PM »
good point frugalgrad--It sounds like way too much work to figure that out--I'm no engineer! I suppose I could send around a survey about shower habits and look at showerhead flow rates, etc. I used to live in Danville PA...are you anywhere around there? It was a pretty area...

waltworks--Interesting..I hadn't thought about the additional strain on the remaining heaters if I took one out. That would definitely defeat the purpose of saving a few bucks if I cause a cascade of failures!

Your comment makes me wonder if the reason this particular water heater lasted so long is because it was the last in the circuit of four. It may not have fired up much at all except during peak usage times or prolonged periods of nonuse since the water that supplies it is generally already heated by the other three. Anyone have any thoughts on this hypothesis?

waltworks

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Re: How many water heaters for 8plex?
« Reply #7 on: October 17, 2016, 01:34:17 PM »
Have you been flushing sediment from the system? I would assume you'd have more sediment buildup at one end of a series system than the other but I'm no plumber.

-W

clarkfan1979

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Re: How many water heaters for 8plex?
« Reply #8 on: October 17, 2016, 01:58:29 PM »
What is a standard water heater? 40 gallon? 50 gallon?

CareCPA

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Re: How many water heaters for 8plex?
« Reply #9 on: October 18, 2016, 06:44:18 AM »
good point frugalgrad--It sounds like way too much work to figure that out--I'm no engineer! I suppose I could send around a survey about shower habits and look at showerhead flow rates, etc. I used to live in Danville PA...are you anywhere around there? It was a pretty area...
...

We're just a little further northwest of Danville. We moved up here from the Harrisburg area to reduce stress - it's definitely more laid back here, and we're loving it so far.

Jack

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Re: How many water heaters for 8plex?
« Reply #10 on: October 18, 2016, 07:54:59 AM »
There is only space for four in the basement utility area btw.

Without considering other circumstances, I would have voted for 8 water heaters (one per unit, on separate piping circuits and ideally with separate metering for both water and gas). But since the only choices are "four" and "less than four," I vote for four unless you're planning to replace them all with one gigantic commercial-grade heater or something.

By the way, when you say they're piped in series, do they have bypass valves and piping or do you have to shut off all the hot water to remove one? If the latter, I'd suggest taking this opportunity to fix that.

srob

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Re: How many water heaters for 8plex?
« Reply #11 on: October 18, 2016, 08:38:14 AM »
ww -I have not been flushing the water heaters on any of my rentals. That sounds like a good idea though. I have heard of people draining them and vacuuming out sediment etc. Seems like a lot of work though. What do you do?

clrkfn - I believe they are 50 gallon heaters.

frglgrd - Cool. I think that central PA is kind of a hidden gem. And the cost of living/taxes is really low too. There is no traffic, etc.

jack - yes i so wish each apt had its own meter and water heater...that would be ideal and each tenant could pay their own utilities that way. The building is old however, (see pic) and unfortunately the plumbing hardware and setup is too. Fortunately they do pay for their own electricity which includes heat. So the gas only comes out to 60ish a month total and I pay that, as well as the water/sewer bill which runs about 100 total for the building. There is no bypass mechanism, just 1/4 turn shut off valves before and after the bank of water heaters. A bypass would be nice...

waltworks

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Re: How many water heaters for 8plex?
« Reply #12 on: October 18, 2016, 09:39:39 AM »
Generally flushing your water heater once a year is recommended. Sediment is usually what kills them.

You can find lots of videos/instructions online on how to do it, it's not particularly difficult even if you aren't a plumber.

It sounds like there may be a lot of plumbing system deferred maintenance here? In any case, at the very least put in a new heater and have some bypasses plumbed in.

-W

Enigma

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Re: How many water heaters for 8plex?
« Reply #13 on: October 18, 2016, 11:06:45 AM »
I recommend replacing the older water heater with a newer one.  Newer ones are more energy efficient, cutting your costs over time.

srob

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Re: How many water heaters for 8plex?
« Reply #14 on: October 18, 2016, 01:38:45 PM »


Thanks guys. I just got off the phone with the plumber and we are going to replace the leaky one with a similar spec new one..about 900 installed.

 I asked him about flushing the old ones...he said that if I had been doing it every year, that would be a good idea, but now that they likely have buildup, and since they are older, we might cause more problems/leaks by opening up the valves at this point. :/

Incidentally, he said that the one that sprung a leak is actually 30 years old!

ww-  Most of the plumbing supply is galvanized pipe with cast iron drainpipe. I fix leaking pipes/fixtures/valves, install shutoff valves at fixtures, caulk and have replaced the toilet wax seals. Apart from water heater flushing and maybe an annual main drain snake, are there any other plumbing maintenance items that you do regularly?


Jack

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Re: How many water heaters for 8plex?
« Reply #15 on: October 18, 2016, 01:45:15 PM »
Thanks guys. I just got off the phone with the plumber and we are going to replace the leaky one with a similar spec new one..about 900 installed.

What did he say about bypass valves?

srob

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Re: How many water heaters for 8plex?
« Reply #16 on: October 19, 2016, 09:07:01 AM »
forgot to ask him about bypass valves...maybe I'll shoot him a text to see what he thinks

CowboyAndIndian

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Re: How many water heaters for 8plex?
« Reply #17 on: October 19, 2016, 09:42:00 AM »
The main reason for a lot of failures in water heaters is due to leaks. I believe the leaks are caused when the sacrificial anode disintegrates.

So, one more possible maintenance item is to replace the sacrificial anode every 3 or 4 of years.

Here is a you tube video of how-to: https://youtu.be/kIpJDHco7hc

« Last Edit: October 19, 2016, 09:44:52 AM by CowboyAndIndian »

Spork

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Re: How many water heaters for 8plex?
« Reply #18 on: October 19, 2016, 10:56:15 AM »

 I asked him about flushing the old ones...he said that if I had been doing it every year, that would be a good idea, but now that they likely have buildup, and since they are older, we might cause more problems/leaks by opening up the valves at this point. :/


Absolutely true.  The rubber valve seats get old and cracked.  You can get them open and not be able to close them. 

Incidentally, I have also had problems with the newer units that are made with cheap plastic valves where they will fail open -- even if they are exercised regularly.  If you have a choice, get one with a real brass drain and not a cheap plastic drain.

Jack

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Re: How many water heaters for 8plex?
« Reply #19 on: October 19, 2016, 11:08:11 AM »
Incidentally, I have also had problems with the newer units that are made with cheap plastic valves where they will fail open -- even if they are exercised regularly.  If you have a choice, get one with a real brass drain and not a cheap plastic drain.

I believe you made the same recommendation in my water heater thread from earlier, but I ended up with one with a plastic drain anyway (mostly because I forgot your advice while I was at the store, but also because it would have required buying from somewhere other than HD/Lowes and I doubt that I would have been willing to pay that much extra). Nevertheless, I've been thinking about it. Do you think a good workaround would be to buy and attach an extra valve and leave the built-in one permanently open?

Drifterrider

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Re: How many water heaters for 8plex?
« Reply #20 on: October 19, 2016, 11:12:41 AM »
Do some shopping around and see what types of units would best be suited for your complex.

If you were to buy 16 water heats you would be able to write off the taxes for all of them this year.

Remember, the tax "saved" on an expense is never as much as the expense.

For the OP:  I believe you mentioned they were gas heaters.  Have you considered that if you need to replace you go with a demand water heater (tankless)?  I've looked at gas heaters recently and they seem to cost about the same (demand vs tank).  Do you pay the utilities for the hot water?

Spork

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Re: How many water heaters for 8plex?
« Reply #21 on: October 19, 2016, 11:24:41 AM »
Do some shopping around and see what types of units would best be suited for your complex.

If you were to buy 16 water heats you would be able to write off the taxes for all of them this year.

Remember, the tax "saved" on an expense is never as much as the expense.

For the OP:  I believe you mentioned they were gas heaters.  Have you considered that if you need to replace you go with a demand water heater (tankless)?  I've looked at gas heaters recently and they seem to cost about the same (demand vs tank).  Do you pay the utilities for the hot water?

I suspect (but I don't know, really) that when you start looking at tankless that can handle flow rates for an 8 plex, they're going to get awfully expensive, awfully quickly.  Flow rate is what you pay for.

Incidentally, I have also had problems with the newer units that are made with cheap plastic valves where they will fail open -- even if they are exercised regularly.  If you have a choice, get one with a real brass drain and not a cheap plastic drain.

I believe you made the same recommendation in my water heater thread from earlier, but I ended up with one with a plastic drain anyway (mostly because I forgot your advice while I was at the store, but also because it would have required buying from somewhere other than HD/Lowes and I doubt that I would have been willing to pay that much extra). Nevertheless, I've been thinking about it. Do you think a good workaround would be to buy and attach an extra valve and leave the built-in one permanently open?

I don't honestly know.  I have no idea if the brass-on-plastic connection would hold up over time.  I've heard when you mix plastic/brass that you should never have female/metal on male/plastic.  Supposedly this is a recipe for cross threading destruction.  (I think that's what you'd end up with.)  But I'm no plumber.

Jack

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Re: How many water heaters for 8plex?
« Reply #22 on: October 19, 2016, 11:52:53 AM »
For the OP:  I believe you mentioned they were gas heaters.  Have you considered that if you need to replace you go with a demand water heater (tankless)?  I've looked at gas heaters recently and they seem to cost about the same (demand vs tank).  Do you pay the utilities for the hot water?

I suspect (but I don't know, really) that when you start looking at tankless that can handle flow rates for an 8 plex, they're going to get awfully expensive, awfully quickly.  Flow rate is what you pay for.

I think a more important factor is the idea that the more people you're serving, the more likely the usage is to "even out" (to a certain extent). The main advantage of tankless is that you aren't keeping water hot when you aren't using it, but if you've got 16+ people who aren't always likely to be using it at the same time then that factor becomes less advantageous.

Incidentally, I have also had problems with the newer units that are made with cheap plastic valves where they will fail open -- even if they are exercised regularly.  If you have a choice, get one with a real brass drain and not a cheap plastic drain.

I believe you made the same recommendation in my water heater thread from earlier, but I ended up with one with a plastic drain anyway (mostly because I forgot your advice while I was at the store, but also because it would have required buying from somewhere other than HD/Lowes and I doubt that I would have been willing to pay that much extra). Nevertheless, I've been thinking about it. Do you think a good workaround would be to buy and attach an extra valve and leave the built-in one permanently open?

I don't honestly know.  I have no idea if the brass-on-plastic connection would hold up over time.  I've heard when you mix plastic/brass that you should never have female/metal on male/plastic.  Supposedly this is a recipe for cross threading destruction.  (I think that's what you'd end up with.)  But I'm no plumber.

What about a plastic valve (but a better design than the built-in one)?

TheOldestYoungMan

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Re: How many water heaters for 8plex?
« Reply #23 on: October 20, 2016, 08:51:08 AM »
Replacing what works with like kind is always a solid plan.

Lets take a look at other options though.

The current system has a quantity of heat being added to a quantity of water.  A simple way to look at reducing the total number is to add fewer, larger heaters.

Larger ones take up more space, generally it will be a more efficient use of space.  If the space they go in is constrained in a way that won't accomodate the larger size however, that's a problem.

Fewer larger ones will likely be more efficient in terms of energy usage, but you give up redundancy/spare capacity.  A good system is oversized a little, so right now with one down your tenants likely don't notice a difference.  If you change the system to have 3 larger units now when one goes down you're much more likely to be under sized (you lose 25% of your capacity with 4, 33% with 3).

Lets say you have 4, 80 gallon heaters.  That's 320 gallons.  It is possible that there are controls that maximize this usage, completely using up one water heater and then switching to another, but unlikely.  You could invest in such a control system and drop to two 80 gallon heaters, reducing your operating costs by half, but incurring some expense with the controls.  You have more complications here, and fewer people will be able to work on your system.  Not as many youtube videos to tell you how to fix it.

So these permutations continue.  There's a lot of ways to do this, and depending on the specific details there definitely is a right answer that would minimize your costs long term.

But nobody on the internet is going to be able to help you.  You'll need an expert to do a site visit.  And that's going to be some up front cost.  It will likely be worth it, and I'd be surprised if it couldn't pay for itself in 5 or 10 years.  But.  It might not.

Replacing what works with like kind is a solid plan.

srob

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Re: How many water heaters for 8plex?
« Reply #24 on: October 20, 2016, 09:38:14 AM »
thanks for all of the ideas guys!

I hadn't thought about tankless..I know they work well .. that is what I used years ago when living abroad. I am curious about what is available for larger commercial applications. I do pay the gas bill for hot water which is about 60/mo.

The plumber replaced it with a normal residential style rheem water heater yesterday so we are good to go this time. Who knows when the other three will go though!

I attached a pic of the water heater at another property I have which houses about the same number of residents. It is a larger commercial type. I think it would cost more than 5k to replace this thing not including labor. It was built in 1987 so I'm crossing my fingers. I don't know if it uses less natural gas than the others because the gas meter at this property also provides for all the gas ranges in the place, so it is hard to compare apples to apples.

A more intelligent design with controllers is an interesting thought!

Drifterrider

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Re: How many water heaters for 8plex?
« Reply #25 on: October 20, 2016, 09:52:13 AM »

[/quote]I suspect (but I don't know, really) that when you start looking at tankless that can handle flow rates for an 8 plex, they're going to get awfully expensive, awfully quickly.  Flow rate is what you pay for.

I didn't mean one tankless for the entire complex, I meant one for one (total of four).

Jack

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Re: How many water heaters for 8plex?
« Reply #26 on: October 20, 2016, 10:24:12 AM »
I suspect (but I don't know, really) that when you start looking at tankless that can handle flow rates for an 8 plex, they're going to get awfully expensive, awfully quickly.  Flow rate is what you pay for.

I didn't mean one tankless for the entire complex, I meant one for one (total of four).

Fixed quotes.

In the OP's case, the problem with that idea is that they're plumbed in series, not in parallel. If you assumed that the small tankless heaters were equally suitable for heating 100% of the water to 25% of the temperature (i.e., in stages) as they are at their designed task of heating 25% of the water to 100% of the temperature then it would be fine... but I don't know if that assumption holds.

That also raises the question of whether some combination of tank and tankless heaters might work best, depending on the particular distribution of load over time.

Drifterrider

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Re: How many water heaters for 8plex?
« Reply #27 on: October 20, 2016, 01:19:48 PM »
Now having see a pic of his basement:

If it were me, and I could do the plumbing, I think I'd invest in some copper (or pex) and work towards getting each unit supplied with its own source of hot water, and having them pay their own utilities. 

On the other hand, if he is paying only $40 per month to supply everyone, I'd probably not replace the defective unit unless someone mentioned the water was cooler or less.

srob

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Re: How many water heaters for 8plex?
« Reply #28 on: October 21, 2016, 08:42:29 AM »
Thanks guys. I have thought about getting each tenant their own water meter, etc, but the way that it is set up, I would have to tear out the walls and ceilings to do it.

The 8plex gas, water and sewer bill only runs about 160/mo combined, so I don't think that it would be worth the trouble.

However, the other property with the commercial water heater pictured above is in a neighboring town and they bill me a flat water/sewer fee for each unit plus usage, so even though both properties use about the same amount of water and gas for hot water, the water/sewer bill for this property is 500/mo, plus the gas costs. It might be more worth it to do a complete overhaul on this building for that reason, so that I could eliminate that cost.

srob

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Re: How many water heaters for 8plex?
« Reply #29 on: November 14, 2016, 09:42:40 AM »
Just wanted to follow up on this post, here is a picture of the setup, and you can see the newer water heater installed on the right. I originally thought that all four were connected in series, but on closer inspection, they are connected in parallel 2 at a time. The circuit involving the two heaters on the left is shorter than the circuit including the two on the right, so I wonder if the two on the left do most of the work, and what happens when those two run out of hot water? Quarter turn valves are installed on either circuit, so you can shut off one bank of heaters to do repairs and the other two will still function. These old buildings are interesting...
« Last Edit: November 14, 2016, 10:12:49 AM by srob »