We recently renovated a house, bringing it from about 900 sq ft to
about 1800. We kept the original boiler as we were told it was
adequate. It is a Weil Mclean Gold series 3 (P-SGO-3). In the
original house it was steam heat. Now it is converted to FHW
baseboard. There is tankless hot water. We used the house for a
summer prior to the renovation and the shower was always hot and did
not run out.
OK, so now we have a second floor and a new bathroom and shower with a
Moen fixture. The mix on this is as far as it can go. So, I get in
the shower and it is plenty hot, I don't even have to turn it up all
the way. I take a long shower sometimes as I shave in the shower (the
whole head). After about 5 min or so the water will go luke warm,
just on the edge of tolerable. After another 5 to 7 min or so, it
will go back to hot and stay there. The weird part is sometimes it
will stay hot the whole time, but this is becoming the exception more
then the rule. I have a few theories, which may be totally off base:
1. The heating system is calling for heat, thereby diverting away for
whatever heats the water.
2. The shower is not restrictive enough and is overcoming the tankless
system. I was going to try one of those little washer type
restrictors to test this theory.
I have tried turning the mixing valve up, but all that does in
increase the initial hot water temp.