On 2/17/2019 5:07 AM, Alan Holbrook wrote:
The water pressure in my domestic hot water supply has recently dropped to
very low levels. The water temperature is fine and there is no problem
with the cold water supply. When I open a hot water tap anywhere in the
house, the water dribbles out for a while and then suddenly gushes for a
couple of seconds and then reverts to the dribble. I have an oil fired
furnace and a tankless water heater, and when I had a serviceman out
recently for another problem, I described the low pressure problem and
asked him if the low pressure could be caused by something in the
furnace/tankless system. He told me that as long as I had hot water, the
pressure problem wouldn't be in the furnace/water heater, and I should call
a plumber. I'm willing to do that, but before I do I thought I'd ask if
anyone in the NG had any idea of what might be happening. Any ideas?


What do you really have? Furnaces heat air, boiler heat water.

Just a guess, you have hot water heat and the boiler makes the water hot
for the heating system as well as hot water for domestic use. Inside
the box there is a coil of tubing that has the domestic hot water. They
can clog up over time and affect water pressure. If you have hard water
it can be loaded with minerals.

How old in the unit? Look at all the options/. The coil can be
replaced, but, it is foolish if the boiler is old and not very
efficient. In my last house I had a system like I just described. It
was having other problems so I replaced it with a System 2000 made by
www.energykinetics.com. It reduced my oil use by 39% and the savings
paid for it over 7 years. (yes, I tracked it by degree days) It has a
separate tank for holding the hot water and it gave all the hot water
you can ever use.

One more thing. Don't trust the guy that you had out for repairs, he
seems rather limited in knowledge.