Primary secondary not transferring heat

Garfield

I have a grundfos 26-64 f on a triangle tube instinct 199000 btu.  It has 10 feet of 1 inch with 7 1 inch 90s and 4 feet of 1 1/4 inch with 5 1 inch 90s on the loop. It goes to the loop of the originally installed triangle tube solo prestige1.5 inch loop with 6 1.5 inch 90s and the boiler exchanger. The prestige does not work, except for the circulation pump which is a 15-42f.  From there I have a heat exchanger to carwash floor heat that keeps the ice off the concrete floors. I am not transferring enough heat to this exchanger. The instinct runs on low fire I’m assuming about 50,000 BTU with a 10° differential on the boiler itself. 108 to 118 degrees in and out temp.  When the prestige was working it would run on high fire with 18-22 degree delta on boiler. Lot of info. At this point, I suspect that one of my pumps is the wrong size either on the prestige or the instinct. All of this is closely space tees and copper pipe. 

Jamie Hall

What is controlling the output temperature from the Instinct unit? If this is a combi, are you using the heating side or the domestic hot water side?

Garfield

It’s just set at 120 for floor heat in the boiler ch1. 

Ironman

Am am I to understand that you’re pumping from the Instinct, through the Prestige, then to the heat exchanger? If so, that will never get proper flow.

Garfield

Original prestige boiler has a primary loop and new instinct is piped to that loop with closely spaced tees. Then from the prestige loop to the floor heat exchanger. 

Jamie Hall

There is a very remote chance that that arrangement might work. Very remote. Among other things -- man others -- a good bit of the heat produced by the Instinct is going into the Prestige and not helping at all.

May I ask what is probably a silly question? Why isn't the floor heat exchanger piped P.S directly to the Instinct, and the Prestige not in the loop at all?

Garfield

I intended to fix the prestige, but after a lot of time and energy haven’t been successful. 

Jamie Hall

Garfield said:

I intended to fix the prestige, but after a lot of time and energy haven’t been successful. 

Fair enough. But if I may suggest, rearrange your piping so that you are using either the new boiler or the old one, with the other completely valved off. May take a few new valves and fittings, but everything will be much better.

GGross

Pictures please. Agree with Jamie that you should exclude the prestige, maybe build your new primary loop ready to add another boiler in the future with tees and caps if you think you will use 2 at some point. The firing rate of the boiler is telling us that the boiler can keep up with demand, if it is set to 120 and is producing around 118, with returns only 10 degrees lower, it certainly just sounds like you are not getting heat transfer in the heat exchanger. What temperature do you get out of the heat exchanger on the floor side? When you change the piping you should take that heat exchanger out and clean out both sides as well as you can.