We have had several TK2 water heaters installed on recent projects (including 1 on my own house). They claim to deliver hot water within 6 secs but at some outlets it takes up to 30 secs. My house is 50 years old so I thought it was probably the sizing of the gas line or the length of water pipe although it is a fairly short run and is copper. The most recent install is new construction, water pressure is very high, pipes are short runs and the gas line is more than adequate. When water is eventually delivered it is hot but if I’m paying for 185,000btu’s of gas for 30 secs of waiting around for water to rinse my hands something is wrong and is costing me money. Anything I may be overlooking?
Thanks
Replies
Ours fires three seconds after flow starts, then gets to full temp after another three. Sounds like you should talk to Takagi about your unit. It should seem only a little slower to deliver than a tank unit.
what about the cold water in the lines
Feel the HW discharge pipe on the WH as someone else turns on the HW.
See if it is hot within about 6 seconds or not. If it is then the problem is the time for it to flow in the pipe.
And by being there you can tell if the burner is slow firing or not.
Brownbagg is right. It is the cold water being purged from your lines. I saw a house with a takagi where the guy had run all 3/4" hot water lines. I bet it drives him nuts waiting for hot water to purge the cold water from the lines plus the 3 to 6 seconds it takes for the burner to kick in.
the one gripe I have with my tankless takagi is when I shut off the water for a few seconds and then turn it back on I get a 3-6 second "slug" of cold water in the hot supply line. I find i leave the water running more just to avoid this and end up wasting a lot of water.
karl
I don't agree. If properly functioning his unit will take 6 seconds longer than a tank to get hot water to the fixture. If the delay is currently 30 seconds then it would have been 24 seconds from a tank. Assuming he removed a tank and installed the Takagi on the same piping then he should be used to that 24 seconds. I'd check the operation of the unit. It sounds like the gas line might be undersized, since he mentions the possibility, and that will stop it from working correctly. Easy enough to check what's happening at the unit while someone else turns the water on and off.
"I'd check the operation of the unit. It sounds like the gas line might be undersized, since he mentions the possibility, and that will stop it from working correctly."Maybe so but the unit seems to be heating water fine, he just doesn't like the delay. My sales rep once encouraged me to call takagi customer service when I wasn't impressed by the volume of my tk2. Apparently there are some adjustments the can be done by the end user.karl
Try my test. Very simple and no cost way to see if the heater is starting to put out hot water in 6 seconds are not.
I had a problem with my water not being hot enough when I had to furnace or oven on at the same time. I increased the main gas line from 3/4 to 1 " (all the branches are 3/4") and it solved the problem. But from what I have seen an undersized line decreases the temperature of the water not the time it takes to get warm.