lsayre wrote:It's only the wife and I who are at home these days. Both showers have the reduced flow 2.5 GPM shower-heads installed, and our well system keeps pressure at between roughly 50 and 55 PSI. If we still had the three children (now adults) living at home I believe the S130 would not be adequate to both heat the house and supply our hot water needs. In the dead of winter that may also prove to be the case for just the two of us, but for that only time will tell. I'm hoping to leave the HWT turned off for the entire heating season.
In the event that the S130 is not up to the task of both heating the home and supplying our DHW during the peak of the cold weather, would adding an indirect HWT to my spare zone improve anything regarding DHW?
I wasn't implying that your boiler wouldn't handle the household DHW load, just suggesting a temporary "blast" through the coil to demonstrate the real btu requirement of a 5 GPM DHW draw.
An indirect water heater offers storage, so as long as it is sized properly you don't have to heat the incoming cold water in real-time. The same thing can be achieved by circulating between a storage tank (electric hot water heater works good) and the tankless coil. Forum member watkinsdr has a nice setup with an 80 gal. electric water heater and the tankless in his S260, I'm sure he would be happy to share the details if you are interested.
Back to indirects...I have an 80 gallon indirect in my system, and the performance is outstanding. The temperature is very stable, and it only puts a moderate load on the boiler. I could put the indirect on a priority control, but I have not found that necessary.
Perhaps it is time for a "How do you produce DHW with your boiler?" thread.