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Point of Use vs. Recirculating Pump for Hot Water?
Posted on 11/11/14 at 9:05 am
Posted on 11/11/14 at 9:05 am
Anyone know about the pros/cons of recirculating pumps vs. point of use water heaters?
In laws have a gas tankless water heater for their home that works great once it gets going, but they're having to wait a long time to get hot water to the far side of the house where the kitchen and guest bath are located. They're looking into pumps and pou systems, but we don't anything about them. Think their electrical service is 200 amps
In laws have a gas tankless water heater for their home that works great once it gets going, but they're having to wait a long time to get hot water to the far side of the house where the kitchen and guest bath are located. They're looking into pumps and pou systems, but we don't anything about them. Think their electrical service is 200 amps
Posted on 11/11/14 at 9:07 am to Quigley
how long is a long time?
This is the downside of tankless heaters.
Most would add in a point of use, I'm less familiar with recirculating pumps. But if it keeps the water always hot in the pipes that will be very expensive.
This is the downside of tankless heaters.
Most would add in a point of use, I'm less familiar with recirculating pumps. But if it keeps the water always hot in the pipes that will be very expensive.
Posted on 11/11/14 at 9:19 am to Napoleon
It's about 3-4 minutes for the kitchen. Not forever, but much longer than it takes on the other side of the house. On the side closest to the tankless they get hot water almost instantaneously. I'm leaning towards point of use for the reason you pointed out and I'm concerned a recirculating may void the warranty on their tankless, but that's just a guess
Posted on 11/11/14 at 9:25 am to Quigley
For a recirculating system you will need rework how the hot water is distributed. you will need a hot water return line back to the pump/water heater. Depending on how the house is piped this can be easy or near impossible without major rework. IF your hot water is looped under the slab to each fixture, then you will need to get into the walls and run a return line up to the attic and back to the heater, collecting each fixture as you go back.
you need to make a loop. the loop will always be hot, and the distance from the loop will determine how long it takes to get hot water.
if you get a POU and place it under your sink, you will need to add a restrictor into the aerator to reducre flow in order to give the heater time to raise the temp. for a 120V outlet, you can get a 3.5kW unit.
with a 3.5kW heater you get less then 0.5 GPM with a 50 degree temp rise (60 - 110)
you need to make a loop. the loop will always be hot, and the distance from the loop will determine how long it takes to get hot water.
if you get a POU and place it under your sink, you will need to add a restrictor into the aerator to reducre flow in order to give the heater time to raise the temp. for a 120V outlet, you can get a 3.5kW unit.
with a 3.5kW heater you get less then 0.5 GPM with a 50 degree temp rise (60 - 110)
Posted on 11/11/14 at 9:27 am to Quigley
Most recirc systems need to go in during rough-in, and they negate most of the advantages of on-demand water heaters. Sounds like point of use would be better for kitchen, although not sure if it would have the capacity for master, eg filling the tub.
Sounds like a poorly located/thought out hot water system unfortunately. New construction?
Sounds like a poorly located/thought out hot water system unfortunately. New construction?
Posted on 11/11/14 at 9:30 am to tigeraddict
Thanks Plumbing is crawl space and easily accessible so that shouldn't be too bad. Flow restrictions and increase demand on electrical service seem to be main downsides of pou systems
Posted on 11/11/14 at 9:34 am to Quigley
since there is no tank, a recirculating pump would just recirculate cold water, or if it pumps through the heater, it would run almost constantly. one way does nothing for you and the other defeats the economy of a tankless.
Posted on 11/11/14 at 9:35 am to halleburton
quote:
Sounds like a poorly located/thought out hot water system unfortunately. New construction?
It's a 1960ish house that they're updating. 4700 sq. ft ranch with everything really spaced out. Father in law hates the damn place, but his wife loves it so he's trying to keep her happy. The guy that put in their tankless is their old plumber and not sure if he thought it all the way through with the kitchen and guest bath so far from the main heater.
Posted on 11/11/14 at 9:38 am to Quigley
Put in a second smaller tankless for the kitchen and guest bath.
Posted on 11/11/14 at 9:50 am to Quigley
I would just add a second tankless. Most of the times I have seen people replace a tank with a tankless they have had to add two.
Unless the plumbing was designed with the tankless in mind.
I have a god candidate house for tankless. My HW line forks to the kitchen and downstairs bathroom. then goes up and hits the laundryroom and the two bathrooms so the run is very very short as the tank is centrally located between them. If your house is large or wet rooms aren't central in the house, then you should just get a second tankless.
Unless the plumbing was designed with the tankless in mind.
I have a god candidate house for tankless. My HW line forks to the kitchen and downstairs bathroom. then goes up and hits the laundryroom and the two bathrooms so the run is very very short as the tank is centrally located between them. If your house is large or wet rooms aren't central in the house, then you should just get a second tankless.
Posted on 11/11/14 at 10:30 am to Napoleon
Thanks. Gonna go down to our local plumber's wholesale talk to them and see what they've got. Went to school with him so hopefully won't screw me too hard
Posted on 11/11/14 at 10:33 am to Napoleon
quote:
how long is a long time? This is the downside of tankless heaters.
Possibly 5-10 seconds longer than having a tank but the benefit of endless hot water. Having the right size tankless is a huge problem for many where they want to save money on the front end and cut corners with a smaller unit.
Having long runs regardless of what kind of hot water heater you have will take time to get hot water to them.
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