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Old 02-27-2010, 06:43 PM   #1
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Tankless Water Heater


I have just moved into a brand new house. It's a 3 storey house with the bottom storey being a kinda basement (even though this bottom storey is above ground) with the other 2 storeys being the regular 2 of a traditional 2 storey house. The house has a tankless water heater that is located in the basement. The master bathroom being on the top floor is, therefore, quite a long way away from the water heater. My dilemma is using the master bathroom. When my wife or I want hot water out of 1 of the master bathroom wash basins or want to take a shower then we need to open the hot tap for approx 4-5 mins before we finally get hot water running. Sometimes, even though only 1 of us wants hot water we have been known of going to the extent of running both basin taps as we believe this gets us hot water faster. I am sure hot water takes so long to arrive because there is so much cold water in the pipe between the heater and the tap. But this seems like such a waste of water especially considering that I live in the greater Los Angeles area where water is scarce. Can anybody help me get hot water alot faster than what I am currently getting it??? Please!!!!

-Welshie

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Old 02-27-2010, 07:03 PM   #2
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Do you have good water pressure? If you do, that water should be moving through the pipe pretty quickly. The cold water between the heater and your faucet should be flushed out in 15 seconds or less. If you're waiting as long as you say you are, there has to be some other problem.

How's the hot water in your kitchen sink? Do you have another bathroom? If so, how's the hot water there?

Also, do us a favor and give us some info off the water heater itself, like the brand name, model no, etc...

Last resort - if the house is really brand new I would contact the builder and tell them what's going on. If they were aware of it taking 4-5min for hot water to reach your master bath then that's unacceptable.

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Old 02-28-2010, 01:17 AM   #3
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Originally Posted by welshie View Post
I have just moved into a brand new house. It's a 3 storey house with the bottom storey being a kinda basement (even though this bottom storey is above ground) with the other 2 storeys being the regular 2 of a traditional 2 storey house. The house has a tankless water heater that is located in the basement. The master bathroom being on the top floor is, therefore, quite a long way away from the water heater. My dilemma is using the master bathroom. When my wife or I want hot water out of 1 of the master bathroom wash basins or want to take a shower then we need to open the hot tap for approx 4-5 mins before we finally get hot water running. Sometimes, even though only 1 of us wants hot water we have been known of going to the extent of running both basin taps as we believe this gets us hot water faster. I am sure hot water takes so long to arrive because there is so much cold water in the pipe between the heater and the tap. But this seems like such a waste of water especially considering that I live in the greater Los Angeles area where water is scarce. Can anybody help me get hot water alot faster than what I am currently getting it??? Please!!!!

-Welshie
Look into a recirculation line, it should help fix the problem.
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Old 02-28-2010, 11:11 AM   #4
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Originally Posted by fetzer85 View Post
Do you have good water pressure? If you do, that water should be moving through the pipe pretty quickly. The cold water between the heater and your faucet should be flushed out in 15 seconds or less. If you're waiting as long as you say you are, there has to be some other problem.

Tankless water heaters work on the principle of flow restriction. The greater change in temperature needed, the slower the water flows through the heater in order to get it 'instantly hot'. Depending on your incoming water temperature you could be flowing pretty slowly.

Now take into account the fact that your tankless more than likely has a 1/2" coil inside of it feeding what's probably a 3/4" line all the way upstairs. You now have to purge that 3/4" line with only the volume of hot water a 1/2" line can produce. This also takes more time.

Unfortunately with a 3 story building a recirc system is not really an easy option without either exposed piping, lots of soffiting, or a whole bunch of demolition to sheetrock to gain access to the walls. And you can't put a recirc system on a tankless without adding a storage tank (conventional water heater).
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Old 02-28-2010, 11:57 AM   #5
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Look into a recirculation line, it should help fix the problem.

Bad idea, tankless water heaters save energy by only heating water when there is a demand. With a recirculation system the WH would run almost continuously.
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Old 02-28-2010, 03:27 PM   #6
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Hi Guys,

Thanks for all the replies. To Fetzer85...Yes we have good water pressure. The hot water in the kitchen is better than the upstairs bathrooms. Not great but definitely better than upstairs. The house has 2.5 baths with the 0.5 bathroom being downstairs. I just ran the guest bathroom upstairs and it took approx 2.5 minutes to get water hot water to come through. And bear in mind it's midday here so we've been having hot water running through the system so far this morning. This (further from heater = slower for hot water) is how I reached my conclusion that it's the cold water purging that is causing the delay in the hot water.

The tankless system is manufactured by a company called Takagi and the model number is the T-K3. I have taken a few photographs here. Just 1 thing to notice in the photographs....(in my layman eye) through the myriad of elbow joints etc etc the pipes seem to go from 0.75" to 0.5" and back and forth until the 0.75" pipes eventually take off towards the upstairs. Surely, then the system can only perform as good as it's weakest link (the 0.5" pipe)???? See photo's.

Would love to hear what people think after the above/photos.

-Welshie
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Old 02-28-2010, 07:28 PM   #7
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I have a similar issue with the baths at the far end of the house - same behavior with a tank water heater and the large Bosch tankless that replaced it. Planned is a new addition of master suite with new bathroom - I intend to add a smaller electric on demand heater at that far end of the house. It will heat the water immediatly, then drop out when hot water from the main heater reaches it.
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Old 03-01-2010, 10:35 AM   #8
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Could try point of use water heater for the sinks; just a much smaller electric water heater mounted under the sink on the hot supply line. As everyone is stating, tank or tankless isn't the issue; the distance from heating source to usage point is.
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Old 03-01-2010, 05:06 PM   #9
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That gas line I think is suppose to be 3/4" to the unit. It looks smaller to me?
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Old 03-01-2010, 05:37 PM   #10
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Quote:
Originally Posted by welshie View Post
Hi Guys,

Thanks for all the replies. To Fetzer85...Yes we have good water pressure. The hot water in the kitchen is better than the upstairs bathrooms. Not great but definitely better than upstairs. The house has 2.5 baths with the 0.5 bathroom being downstairs. I just ran the guest bathroom upstairs and it took approx 2.5 minutes to get water hot water to come through. And bear in mind it's midday here so we've been having hot water running through the system so far this morning. This (further from heater = slower for hot water) is how I reached my conclusion that it's the cold water purging that is causing the delay in the hot water.

The tankless system is manufactured by a company called Takagi and the model number is the T-K3. I have taken a few photographs here. Just 1 thing to notice in the photographs....(in my layman eye) through the myriad of elbow joints etc etc the pipes seem to go from 0.75" to 0.5" and back and forth until the 0.75" pipes eventually take off towards the upstairs. Surely, then the system can only perform as good as it's weakest link (the 0.5" pipe)???? See photo's.

Would love to hear what people think after the above/photos.

-Welshie
2.5 minutes? Are you timing this by hand or just guesstimating? That's way too long. I have an exterior mounted Noritz 7.5GPM and it takes 30 seconds or less to get the water upstairs. For the sink that is closest to the heater, usually 15 seconds or so.

I would look into getting your unit checked out by a qualified repair person.

Maybe as a test you should have someone stand by it when you turn the hot water on and see how long it takes to fire up. Mine fires off the gas as soon as the hot water is turned on.

http://www.noritz.com/homeowners/pro..._water_heater/
I have the outdoor model.
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Old 03-03-2010, 12:11 AM   #11
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Hi Brons2,

I timed it with a watch. It's accurate +/- 15 seconds. And that was middle of the day when we'd already been using hot water upstairs earlier in the day. It's more than that first thing in the morning.

I'm out of town for a few days now, but after the weekend when I return home I'll measure the pipes and let people know. Sounds to me like something is wrong so maybe I need to get a professional in to take a look at it.

Any additional comments welcomed.

Thanks Guys,

-Welshie
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Old 03-03-2010, 02:47 AM   #12
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Do you know what the temperature setting is on? If you don't have the manual, you can find it on the Tagaki website.
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Old 03-03-2010, 01:46 PM   #13
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get recycle pump with a timer. set the timer for only the times in the a.m. that the need for hot water is the greater distance. The rest of the time the unit will stay off. Also find out the gas pressure at the unit when calling for at least 3 gpm. most of the unit don't work well with less than 5 "wc. you can upgrade your meter to 2psi and use a regulator to get the correct pressures. You need a technician that is trained on tankless heaters. It will be well worth your money to get it right.
Good luck

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