Tankless water heater

[Lawrence Taylor]

Condo remodel:
*100amp service
*208 voltage (getting 205 in the apt. confirmed by 2 probes).
*#6 wire(maybe a 20 foot run)
*60amp breaker for a unit that is speced for 54amps
This TWH will only fully heat the water when we damper back the water supply to say 50%. otherwise water is luke warm at best.
When calling for hot water this 208v unit is drawing 47 to 48 amps. With all equipment in the appartment running together the draw on the appartment is 91 to 95 amps. No perceptable voltage drop during the time we metered the appartment. All equipment is in good working order. I have been recommending these units to customers and have been trouble free for all five other installs. My electrician does not know what to make of it. My Plumber can only recommend that all the air is perged from the supply lines. Did that. This unit is speced to handle 3psi all the way to 150psi. I d seriously do not think I have more than 100psi in this appartment.
Any thoughts on why this unit is not heating properly (its the second one from the manufacturer). The manufacturer also is stumped.

[BigB56]

Re: Tankless water heater

It looks like it is drawing close to it's full load amps, you will probably need to reduce the GPM. Plus a 60 amp unit is not very large. What is your incoming water temp? I have installed Seisco 100 amp units (91A FLA) in 2 bedroom apts and we always install low flow shower heads, even in AZ where the incoming water temp is warmer than most places. remember the incoming temp is going to make a big difference, along with the GPM. The unit paperwork should have a chart that tells what the temp rise is at various flow rates in GPM. You can't go by PSI, you will need to determine your actual flow rate in volume.

[BigB56]

Re: Tankless water heater

Is this the first install on 208? Is the unit rated 208/240? If so, is the 54A spec at 208 or 240? also, at which fixtures are you testing, kitchen etc.. These units cannot keep up with a full open unrestricted flow like a bathtub or a laundry tub.

[Lawrence Taylor]

Re: Tankless water heater

First unit was rated 240. Then we realized the 208 voltage and swtched. Yes this unit does spec for 54 amps @208.In coming water temp has never been an issue before as this is South Florida. When I get back to the job site, Iwill try to find the spec. sheet for this TWH . Manufac. says this unit does not require a flow restrictor.

[Lawrence Taylor]

Re: Tankless water heater

My shower heads are 2.9gpm
My rise chart says I will have a 35 degree rise in temp. I need to get my incomming temp. I'll be back

[BigB56]

Re: Tankless water heater

First off, 2.9 GPM is a lot of flow for a 50 amp unit. It would be helpful to know what brand & model it is. For example, the Seisco 50 amp unit has a max flow rate of 1.5GPM and is not recommended for whole house/apartment. The smallest recommended for whole house is the RA 22 which is a 91 amp unit. Even with that there are limitations.
Second, if tech support has no answer for you they are lame and I would send it back and go somewhere else.

I am thinking with the flow rate you have, you don't have a big enough service to power the right size unit. You are already pushing it to the limit with a 100 amp service.

[Lawrence Taylor]

Re: Tankless water heater

I am not going to disagree with that. Its just that I have installed a few of these with out inncodent. This model is capable of hot water for 2 full baths,dishwasher, cloathes washer. Titan is the name of the company, I am waiting for their trouble shooter to get back to me.

[Lawrence Taylor]

Re: Tankless water heater

This is the unit. the N-120
http://www.titanheater.com/tankless_water_heater.php

[BigB56]

Re: Tankless water heater

At 48 amps and 208 volts you have less than 10KW. The rise chart is figured at 11.88KW. I just think the unit cannot heat fast enough for your flow rate. You will have to install a 1.5GPM shower head.

[jwelectric]

Re: Tankless water heater

Based on the flow chart and the flow rate you have posted it looks as the water will be lower than the body temp which would feel cool to the person taking a shower.

My shower heads are 2.9gpm
My rise chart says I will have a 35 degree rise in temp. I need to get my incomming temp. I'll be back

To have 100 degree water the incoming water would need to be 65 degrees.

At 48 amps and 208 volts you have less than 10KW. The rise chart is figured at 11.88KW. I just think the unit cannot heat fast enough for your flow rate. You will have to install a 1.5GPM shower head.

Sounds like the best advice you will get to make this unit work for the shower but this won’t do much for the other fittings such as sinks,

[Lawrence Taylor]

Re: Tankless water heater

Why do you think this unit is only drawing 48 vs 54 amps? Just not enough umph to the panel?
The rep from Titan implied that they can build me a unit to work. Think thats possible or his he yanking my chain

[BigB56]

Re: Tankless water heater

Why do you think this unit is only drawing 48 vs 54 amps? Just not enough umph to the panel?
The rep from Titan implied that they can build me a unit to work. Think thats possible or his he yanking my chain

It must use the same elements as the 240 V model, which are 4.4 ohm elements. At 208 V the 4.4 ohm elements will use 46.8 Amps, and produce only 9734 watts.

[BigB56]

Re: Tankless water heater

I'm not so sure another 3,000 watts would solve your problem. With the power you have available I still say you have to reduce the flow rate.

Keep in mind if they build you a unit that heats more, the amp draw will increase and you are already loaded up pretty high for a 100 amp service. Your electrician will need to do a load calculation.

[Lawrence Taylor]

Re: Tankless water heater

Thanks for the input fellas. I am gonna feel like a horse's ass if I have to put the old school WH back in the closet. I'll let you know after.

[jwelectric]

Re: Tankless water heater

Please do keep us updated.