Sanity Check

SalusSolutions

Good Afternoon Forum,

I moved into a house that has hydronic heating loops in the concrete floors. The existing wood boiler system and water pump were removed and we connected a tank-less water heater and installed a Taco 0011-F4 circulator pump.

There are 4 loops on the second floor, and 4 loops on the first floor. The Taco pump pushes water 16' up to the tank-less water heater, then the whole system is downhill (gravity) after that, except 5' uphill at the end as water returns back into the storage tank.

The whole system is designed in this order:
1) Water storage tank (vented to air)
2) 3/4 Quest pipe
3) Taco pump (0011-F4)
4) 3/4 Quest pipe
5) Tank-less water heater (14' above pump)
6) 3/4 Quest pipe
7) Second floor supply manifold (4 feet below tank-less heater)
8) Second floor loops (4 each, 1/2 Pex)
9) Second floor return manifold
10) 3/4 Quest pipe
11) First floor supply manifold (16' feet below tank-less water heater)
12) First floor loops ( 4 each, 1/2 Pex)
13) First floor return manifold
14) 3/4 Quest pipe
15) back into the storage tank (vented to air)(5' above the first floor loops)

My questions are, I can't get enough flow through the system, which of these below scenarios seem most likely to be the problem? And might you have any recommendations?

1) The circulator pump is BEFORE the manifolds that splits into 4 loops (see photo). The return of each loop feeds back into a return manifold, then the water moves to the second floor and into another manifold with 4 more loops. Could this be the cause of the flow problem?

2) Is it probable that I just haven't bleed the systems completely?

3) Is it possible that the Taco 0011-F4 isn't pushing enough water?

Thank you for any guidance you might offer!

Henry

Sorry but why was it not inspected before you moved into this disaster?

nicholas bonham-carter

The tankless water heater is not designed to provide hot water for heating: it provides a small flow of water with a large temperature rise, whereas a boiler is designed to provide a large flow with a smaller temperature rise.
From your description of the system, it seems that when a real boiler is installed, it will need some repiping to make it work.—NBC

GBart

what kind of plastic pipe is that?? does it all have an O2 barrier?

DZoro

post pictures of the tankless piping arrangement

billtheplmbr3845

I agree with GBart. I don't think there is a o2 barrier. Loops could be plugged up. Ran into this scenario a couple of years ago. Had to get the lines clear and add a plate heat exchanger because most of the pipe was not accessable. 0011 should push more than enough gpm. Any idea how long the loops are, looks awful home ownerish.

Ironman

The 011 will not push enough water through a tankless because of the extremely high head of its heat exchanger.

The piping is Qest which should never have been used for radiant. It has no O2 barrier. It also had a total recall and a corrective action program.

The best long term solution is to install a real boiler and new radiant tubing. If doing the tubing is impractical, at least isolate it with a heat exchanger.

It's this kind of hackery that gives radiant a bad name