Forum
« Security and the Front Door SRO conversion to two family »
November 18, 2008
Hot water for sinks/shower
We just moved into a 3 story 2.5 bath brownstone. The hot water takes about 30 seconds to reach the shower and even longer for the smaller faucets (b/c the pipe has to empty of cold water before the heater water gets there). I feel like we're wasting water every morning and would like to have the convenience of quick hot water for the shower. I've looked at "comfort pumps" which use the cold water line as a return line and keep recirculating hot water from the heater, but noticed most are designed for long houses and not high ones. I talked specifically with a person at a plumbing supply store and he said the max "head" for the pump is about 30 feet, close to which the pump can't handle the water. My question is: has anyone had these installed without getting a specific hot water return line. If so, which model (we heard grundfos is the best). Any recommendations from a plumber would be helpful as to what the options are for a tall house (3 stories) and not wanting to tear apart the walls to put a return line in.
Does everyone else just wait for the hot water? I'm assuming this is common on all the older building with dated plumbing.
Comments
It is common also for new houses with new plumbing.
You could put 'on demand' water heater in bathroom but could take longer than your lifespan to recoup the investment. But if you makes you feel greener...
Or could just take shorter colder showers save money and be green.
Posted by: Petebklyn at November 18, 2008 2:45 PM
So assuming the on-demand thing doesn't work (no space for the unit) and I don't want to take cold showers in the middle of the winter...
Point is that newer houses have the option of putting in a hot water return line so that convection can just keep the hot water flowing in the pipes. I'd have to tear up some walls to install new piping...
Posted by: justinm at November 18, 2008 2:49 PM
Is waiting 30 seconds for hot water that much of an inconvenience???? God, I pity your spouse or significant other.
All the other options you mentioned are going to waste energy.
Posted by: daveinbedstuy at November 18, 2008 3:07 PM
Dave - I'm sure that it's not the inconvenience so much as the feeling that a lot of water is being wasted while waiting for the hot water to make it up three flights for each shower (not to mention the double digit rate increase on water use).
Posted by: SenatorStreet at November 18, 2008 3:30 PM
The wastage of water should be far less of a concern money wise than the wastage in energy for immediate heating. If your water bill is anything more than a mere fraction of your heating bill then something's very wrong.
Posted by: daveinbedstuy at November 18, 2008 3:33 PM
Yeah... I really see it as a tradeoff between wasting water and wasting heat in the pipes/pump. The pipes can be insulated and the pump uses hardly any electricity.
But it also is a question of convenience. On the top floor the faucet takes much longer because lower throughput. It's just the shower that takes 30 seconds. What's so wrong with wanting hot water shortly after I turn the hot water faucet on?
Posted by: justinm at November 18, 2008 3:36 PM
Had I thought about this prior to renovating the top floor master bath, I would have looked into the smallest electric point of use heater I could find. I would have plumbed the hot water from the basement into it on its way to the shower. Instant hot water and once the hot water made it to the unit the point of use unit would cut off. Probably never break even financially, but instant hot water is a luxury -- the same as my heated mirrors!
Posted by: SenatorStreet at November 18, 2008 3:48 PM
Justinm,
"Head" just means resistance to flow and the height of the building has nothing to do with it.
The weight of the water the pump needs to lift is effectively countered by the weight of the water the pump returns to the water heater in a closed system.
If the pump can overcome 30 feet of head (that's a lot) then that little Grundfos can certainly supply you with the 0.5 gallons per minute needed to deliver hot water efficiently to your farthest fixtures.
This is not a guess. This is me:
www.GatewayPlumbing.com
Posted by: Master Plvmber at November 18, 2008 4:05 PM
I keep 2 gallon jugs in the bathroom & fill about 1 & a half each day while waiting for the hot water. I use the collected water to water plants or even fill the reservoir on the toilet after a flush. Minimal conservation but it makes me feel good.
Posted by: Arkady at November 18, 2008 4:21 PM
Run the shower while you're pooping.
Posted by: daveinbedstuy at November 18, 2008 4:25 PM
Back to the topic at hand (not alternatives, as ridiculous as they may or may not be)... Master plvmber, what does this mean for a system that has a valve at the topmost bathroom that allows water from the hot water line to go one-way into the cold water line, effectively using that as the return line? (this is for systems with a pump on the hot water line on top of the water heater). (the question was about head pressure, which in this case I believe is equal to the height of the house -- I'm probably wrong though).
Posted by: justinm at November 18, 2008 4:40 PM
What this means is that regardless of where a pump is in a closed system, the head pressure remains constant. It doesn't matter where the valve or pump are installed.
I've never been a fan of dumping hot water into a cold water line, but even I realize that that's just old-school thinking. There's really nothing wrong with it, especially if you're using a newer, cleaner method of making hot water.
By the way, for comparison's sake, a pump in an open system, say a sump pump or a fire truck, has to grab water from some source and lift it through an open ended conduit where it is ejected from the system.
This is called a positive displacement pump.
In heating systems and in this application, the pumps are not capable of "lifting" water at all. They don't have to. They just influence the flow of water through a circle. That's why we call them circulators. They're not really pumps at all.
Posted by: Master Plvmber at November 18, 2008 6:06 PM
Ok. I get it. So the only think causing "head" is the difference in pressure in the cold/hot systems plus any resistance on the lines in the way of bends and t's.
I think this answers my question... Since it's only a 2.5 bathroom I'll do the smallest model and return it if it doesn't work.
Has nobody else done this before? It gives instant hot water and it just a retrofit of existing systems...
Posted by: justinm at November 18, 2008 6:31 PM
Lemme ask a stupid question here... why not install a thermostatic shower head? That won't help with the faucets but it may with the shower. Not sure what it takes to install one tho.
Posted by: denton at November 18, 2008 7:14 PM
True recirculation does waste energy...I thought you were considering a gizmo that dumps water from the hot to cold lines only when you push a button to require it.
This is a pump easily plumbed in (you could almost do it yourself) which runs as long as the hot water line has cold water, then stops. Now, you still have to wait, but you're wasting no water nor energy.
The cheapest one is Chilipepper (abt 200); looks toy-ish but has gotten good reviews; somewhat noisy; remote control for II bathroom.
http://www.chilipepperapp.com/howit.htm
Posted by: cmu at November 18, 2008 8:19 PM
Cmu, many units, such as the Grundfos mentioned earlier, have a built-in aquastat that do pretty much the same thing as the description on the Chilipepper unit: shut the pump down on temperature rise.
Posted by: Master Plvmber at November 18, 2008 9:04 PM
Master Plumber... am I right to assume that the smallest grunfos will probably work with my house? Is there a significant possibility that it won't?
CMU -- Master plumber is right the grundfos can either run on an aquastat or a timer or both, effectively only doing it during waking hours and only enough to heat the line.
I've heard there are other activation options, such as a motion sensor, but I don't want to get that high-tech...
Posted by: justinm at November 18, 2008 9:40 PM
Again, you don't need much flow for recirculation, justinm.
I'm sure you don't need anything other than the smallest Grundfos, which I think is the UP-15 series.
Seriously, don't over think this.
These things are made to work in the application you're describing.
Posted by: Master Plvmber at November 18, 2008 9:47 PM
Ah, I see. So the minor difference is that the chillipepper never wastes energy since you have to turn it on explicitly with a switch (j: nothing hi-tech there) but the Grundfos will restart and refill the hot riser from time to time if its timer is on?
Posted by: cmu at November 18, 2008 11:27 PM
Post a comment
Please be patient while your comment is published. It may take a moment.