AHNC
Gold Member
While I understand the thinking on the "smallest diameter" it does a couple things that will make hot water more costly. It is largely a vol/waste/wait issue. Larger tubing means more water/heat waste while waiting for hot water. 100' of 3/4" can hold 2.5gal. 1/2"=44% of that. Here in MA the Charles River and Boston Harbor clean-ups are worthwhile projects, but by golly we are paying for it in some of the highest water rates in the country. We talk about energy conservation, but while we can get along without "hot" we cannot get along without "water"! Standing at the tap waiting for the hot to arrive is very costly. Insulate your pipes, do it well! Get your water heater as close to the point of use as possible.
I make a living selling tankless water heaters. Primary in their application is water testing. Look before you leap. Treat your water if necessary. Keep in mind, that everything in the house is affected by poor water quality. If you are unwilling to do so, then don't get a tankless. Buy a cheap tank and replace it regularly, because the water will affect that too. Feed tankless decent water and you will be well served.
As to the hot water heat pump, I'm going to look into it a bit more and I'll post my findings. One thing I do like about them is that they will help dehumidify a basement in the summer months. From a temperature standpoint they are internal to the space so the 40-90F is not an issue...I hope!
The 40-90 temp limit also does not apply to SOME of todays heat pumps. I'm in the business so I fire what I sell. I'm running my mini-split heat pump cost effectively down to 15F, but I'm usually over to gas at around 20-25. I've been in this house 17 years and have had 4 different boilers and am putting in another in the next couple weeks. As well, I have three gas fired direct vent wall furnaces. No self-discipline...thats my problem!
