Taco HotLinkPlus-e recirculation system question.

Jean-David Beyer

I am about to have a Taco HotLinkPlus-e recirculation system installed for my hot water system in my house. It includes an ECM circulator, a clever valve connecting the hot water line to the cold water line at the furthest fixture in the system, a thermistor sensor and a "Smart Plug" that controls the power to the whole system. I have read the brochure and the instruction sheet for these units, but as a homeowner, I choose to have this installed by a professional (who currently services my hot-water heating system).

Now what the smart plug unit does is notices when hot water is being used and stores this information within itself for a week. It then runs the circulator at those times the next week. The thermistor tells the smart plug when hot water is being used. The use times are continuously updated automatically after that.

But I would like to know, in more detail, just how the smart plug actually works. I do not exactly want a wiring diagram that might be proprietary anyway, but I would like enough detail so I could tell the best way to make my usage patterns make the unit work best.

One way it might work is that it might have a little memory with 168 slots in it, one for each hour of the week, and it stores just whether the system was supplying hot water then. Then the next week, for those hours when hot water was demanded, the circulator would be switched on. It would be better if it switched on a few minutes before hot water was used so the water would be hot at the fixture when needed. I doubt this is actually how it is implemented, but I sure would like to know how it actually works.

bob eck

Smart plug gets plugged into a outlet and pump gets plugged into the smart plus. A wire comes off the smart plug with a sensor on the end of the wire. The sensor gets strapped to the hot water supply line coming out of your water heater. As you use hot water during the day the smart plug learns for 7 days what time of day you use hot water and then the smart plug will turn on the pump so you have hot water at your faucets without waiting for hot water and you are not wasting water down the drain while waiting for hot water to shower with.

Dave H_2

The SmartPlug learns "events". What that means is it looks for a temperature rise in the pipe, a duration of high temp, then a temp fall. The unit then stores this as an event.
The SmartPlug has a 7-day calendar and can store as many events that occur during the day.

So for example, it learns that a shower was taken at 6:30 am on Monday.
The following Monday, the SmartPlug will turn on at 6:00am and turn off at 7:00am in order to give you a window of opportunity to take your shower on Monday. We all don't stick to our schedule so rigidly.
But during that hour, the SmartPlug turns on and off the circulator; 5 minutes on/10 minutes off, 5 minutes on, 10 minutes off (the water is not going to cool down that fast in 10 minutes).
The device is also very hungry for data and always learning and adjusting based upon your schedule and habits.

Dave H.

SteveSan

Great explanation Dave and Bob. I would like to add one thing and correct me if i'm wrong. As far as a "timed event" is it must be more than 5 minutes like a shower, dishwasher, or hot cycle on the washer. It won't remember just washing your hands for a few seconds. This would prevent the pump from coming on more than needed.

Dave H_2

@SteveSan , exactly right.

However, if you do want the system to give you hot water all the time for just those quick hand washing events, then you can switch the SmartPlug to the pulse mode.
The pulse mode is just 5 minutes on/10 minutes off all day/all night rather than 24 hours a day.

Dave H.

Jean-David Beyer

So for example, it learns that a shower was taken at 6:30 am on Monday.
The following Monday, the SmartPlug will turn on at 6:00am and turn off at 7:00am in order to give you a window of opportunity to take your shower on Monday. We all don't stick to our schedule so rigidly.
But during that hour, the SmartPlug turns on and off the circulator; 5 minutes on/10 minutes off, 5 minutes on, 10 minutes off (the water is not going to cool down that fast in 10 minutes).

Thank you for that explanation.
What inspired me to get the system was by watching my new diswasher's water use. What it does varies a bit depending on how dirty the dishwater gets. But its water use is a bunch of short spurts. It fills the system which takes a minute or so and rinses for about 8 minutes. It may drain it then if the water is dirty and refills. Then it washes for about 25 minutes. Drains and refills and rinses for about 6 minutes, drains, refills and does a long rinse. The whole cycle is 2 hours and six minutes, but the drying phase is a large part of it.

But in my house, the temperature of the hot water supply (from a 40 gallon indirect running at 140F, but mixed down to 120F) drops considerably in 5 or six minutes (the water lines are buried much of the way in my concrete slab that is a big heat sink.

My contractor will install the system Thursday, so I will find out.

Jean-David Beyer

As far as a "timed event" is it must be more than 5 minutes like a shower, dishwasher, or hot cycle on the washer. It won't remember just washing your hands for a few seconds.

Then will not my dishwasher confuse it? It is proud of the fact that it uses so little water (only hot water is even connected to it). It never runs hot water for as much as 5 minutes at a time. perhaps one or two minutes max. Does this mean that the the SmartPlug will think that some people washed their hands a few times and ignore what my diswasher was doing over a two-hour interval?

Dave H_2

@Jean-David Beyer That depends upon the SmartPlugs math and "confusing it".
The SmartPlug software really is a function of length of time and rate of change in increase water temp, offset by drop in water temp and rate of change water temp drops.

It's got an algorithm that is doing the work behind the scenes. I don't know enough of the code but think of it this way;

It always runs in Pulse mode until it detects continuous/sustained drop in water temp and learns when to stop running.

So its trying to not learn the quick hand washing when you happened to stop at home and such.

Of course all this is predicated that the Dishwasher is run at the same time, every week and there are no other uses of water in that time period. Once you stop and think about, your head starts to hurt thinking about all of the scenarios possible.

Dave H.

Zman

I had a similar grundfos comfort system in my house and disconnected it. My complaint was that although the water was always hot at the faucet, my cold water was always noticeably warm as well. I got tired of waiting to get acold glass of water.
It makes sense when you think that they are just dumping hot back into the cold. The timer on the Taco unit may mitigate some of this but I suspect it will still be an issue.

heathead

You describe getting this for your dish washer. If it is a newer dish washer look at gallons of water it uses, and also if it has a built in heater if water isn't supplied at exactly 120. Most new dishwasher will heat the water. If getting this for the whole house, furthest shower from water heater and don't want to wait for warm water great very nice feature to have, if you are chasing cost savings for dish washer it won't be cost effective. Good luck.

Jean-David Beyer

If it is a newer dish washer look at gallons of water it uses, and also if it has a built in heater if water isn't supplied at exactly 120. Most new dishwasher will heat the water.

That was the inspiration, but not the only reason. My dishwasher has a built-in heater, but the heater makes the cycles longer in order to bring the water up to temperature. The complete cycle for 1/2 load is 2 hours and six minutes. It will always use the heater because the last rinse is at 158F to 162F. It uses 3.4 to 6.4 gallons of water depending on how dirty the dishes are.

Trouble is that the dishwasher is so far from the hot water heater, and the pipes run through my slab at grade, that they cool off fast. I must run a whole dishpan of water to get the water up to temperature of 120F to start. And after a pre-rinse, it may dump the water and refill 6 to 8 minutes later, by which time, the hot water is already cold. Then 28 minutes later it does the first rinse, and six minutes later another rinse (where it will certainly use the electric heater).

But I have similar issues for my washing machine in the winter when I run it at "warm" and just to shower or wash my face and hands in the morning.

Jean-David Beyer

My complaint was that although the water was always hot at the faucet, my cold water was always noticeably warm as well. I got tired of waiting to get acold glass of water.
It makes sense when you think that they are just dumping hot back into the cold. The timer on the Taco unit may mitigate some of this but I suspect it will still be an issue.

I read a lot of complaints on the Internet about this unit. Complaints about how noisy the pump was, how scalding hot the cold water was.

My contractor mounted the pump on the attached garage wall right next to the indirect hot water tank, just below the temperature mixing valve. That wall has my bedroom on the other side, but the wall is filled with polyurethane foam insulation, an the unit was installed yesterday morning. The unit is training itself for a week, so it runs five minutes, stops for 10 minutes, etc. I cannot hear it at all. Actually I cannot even hear it if I am right next to it. A blue LED lights up when it runs.

Downstairs, the dishwasher is right next to the sink, and the clever valve is under the sink.

Upstairs I have a photographic darkroom, even further away from the hot water heater than the dishwasher and kitchen sink. So I had my contractor install a second clever valve up there. There, I can hear the hot water circulating through the 1/2 inch copper tubing when the pump runs, hear the click when the hot water heats the clever valve that shuts it off, etc., but I must listen carefully to tell it from the sound of the wind blowing outside.

Now it does put some hot water into the cold water line, but it is by no means scalding. The temperature mixing valve takes the 140F-160F from the indirect and mixes it down to about 121F at the pump entry. The cold water never gets that hot, but if I do not run it a bit, it is slightly warm and tastes a trifle flat. I am experimenting a bit with that. In particular, I had the ECM pump running very slowly initially, and that meant a lot of tepid water had to go through that clever valve before it closed. It did not even get up to temperature during a 5-minute on-cycle. So I have speeded up the pump to medium speed to see if that valve would shut off quicker. The data are not in, and it may be somewhat different next week as it has gotten used to my water usage patterns, and as I get used to it as well.

Jean-David Beyer

I have another use for this unit.

If it gets really really cold outside, like 0F (design temperature for home heating around here is 14F), one of my hot water pipes can freeze (I would have to remove cabinets and open a wall in my kitchen to insulate that pipe better).

If I know that is coming, it seems to me I can set the unit to Pulse Mode, and that would keep the pipe warm.

My question is: If I set the Smart Plug to Pulse Mode, does it forget my most recent week of use data, or does it switch back automatically?