KNB155 Lochinvar with hard errors

CraigCO

I have a KBN155 that has been installed and working fine for some 5-6 years. Recently in the last 30 days for every error or problem another one comes up.
*TP valve dripping and was replaced with 30psi new valve (still dripping)
*HVAC guy determines that 3 control valves and pressure reducing valve need to be replaced
Unfortunately installer did not put in pressure meter. So….. Assumed pressure reducing valve was left at 15psi. Meter on side of boiler is reading 28psi. Unit is approximately 25 feet from highest bathroom on the 3rd floor.
*Unit going into Outlet Temp Diff lockout.
*Outside temp sensor replaced and Output sensor on heat exchanger replaced. (old one was 2016)
*Expansion tank replaced. (old one was just at 6 years old
*Outlet MRHL Lockout. (have gotten the ARHL lockout but only 5% of the time)

On the fence of it it possible could be the pump . As the way the installing HVAC company originally setup the unit was with 1 pump.

The system if feeding radiant floors on 3 floors and a sidearm hot water tank . Total is (4) zones for the radiant and (1) for DHW.

CraigCO

Here are some pictures for reference.

Jamie Hall

Pressure reading is way too high. You need to verify that the expansion tank is correctly pressurized (lots of comments on that -- basically it has to be isolated from the system and empty of water, pressurized to the system pressure (12 to 15 psi) and reconnected -- and then drain or add water to the system to reach the tank pressure -- and then close the valves from the water supply to the boiler. Run the boiler up to temperature -- the pressure should rise, but not more than a few pounds.

Now you have the pressure tank.

Now leave the feed valves closed. The pressure should not change (except for the heating effect) for at least 24 hours. If it drops below what you set it at, you have a leak. If it rises, water is leaking by the feed valve which you closed and the pressure reducing valve is faulty. So far so good? Open the manual feed valve and observe the pressure again. It should not rise. If it does the PRV is faulty or misadjusted.

Now with all that straightened out, see what error messages you get -- if any. But fix the pressure problem first.

hot_rod

Not enough of the piping is visible , it doesn’t look like it is piped primary secondary?
That boiler data logs all the fault errors, it would tell the story about lack of flow issues if it is mis-piped 

CraigCO

See the attached. I have re-purged the system and verified the tank has no water. So, far pressure is holding but temps not getting what I would call hot. Letting it do its thing for a bit to see.

Error screen was from before the above was done.

Teemok

If the boiler is 25' below the highest heating loop you are going to need to run a higher system pressure than 12-15. 25'/2.31 =10.8 psi at the bottom and zero at the top. 18-20 psi is what I would run. The expansion tank air charge must match this or even slightly exceed it or you will have reliefs leaking. It looks like it's piped primary only with 007. The pump is too small. I fear how long the radiant loops are. The top zones are likely air locked and when the bottoms close there's no boiler circulation. A pressure bypass or even a small fixed one would help things. Looks like your make up water line double check is on the wrong side of the fill valve. Zone valve are on the supply side. Air scoop, ex.tank and water fill point should be between the boiler and the pump. You need a very good pro to look over this whole system and make a priority list of changes needed.

CraigCO

Boiler is located in a mechanical rm in a finished basement. So, from the top floor we are about 25’ assuming each floor is 8-10’. I have the pressures set at 18-19 psi. The system was NOT a homeowner install but from a professional HVAC company. They have a new service tech which is the only person they sent out for service calls. So after 8 trips i’m just a bit frustrated with no fix just throwing parts.

May not be a factory but we are at high elevation (9000’). The unit is a high elevation unit of up to 9600’.

hot_rod

That pump is adequate, but it should be piped like the manual shows

With one zone calling I doubt you get adequate flus and it will lock out

Has it  ever been disassembled and cleaned inside?

CraigCO

It has been working fine up till recently with no issue on any calls to radiant or DHW. Yes it has been dissembled and internally cleaned.

Teemok

"professional HVAC company" I'm so sorry to read this. I don't know what to say. We don't talk prices here but I hope it was very inexpensive. I've spent a fair chunk of my work life fixing the doings of both well meaning, careless and malicious "professionals". There's no shortage of to this kind of thing around. Double edged sword for me. On one hand, it's terrible to see, on the other, it's great job security. Maybe someone in that outfit can make it work but from the looks of things I wouldn't bet on it. The drip leg on the gas is on the wrong side of the valve. Wow. Shakes head and backs away.

hot_rod

CraigCO said:

It has been working fine up till recently with no issue on any calls to radiant or DHW. Yes it has been dissembled and internally cleaned.

Could be a seized pump if it races to high limit
or an air lock

HomerJSmith

Check the installer's programing. Entry into the programing is in the service manual (5309), I believe.
Lochinvar is good at Tech help, call them.
Your controlling sensor, inlet, outlet or sys should be decided upon. Piping as a primary/secondary is the best strategy. The distribution pump should be a ECM pump with zone valves. With a P/S sys you would need 3 pumps, a distribution pump, boiler pump, and a indirect tank pump;
Copper piping should be as simple and artful as possible, not like yours, my belief.
Closely spaced tees separating a P from a S is swell, but I prefer a hydrolic separator for that task.
15psi air charge on the bladder tank is fine and the Pressure Reducing Valve should be set the same.

I only see one pump a Taco what?

hot_rod

You have a conundrum, it is not piped properly, yet has worked for 6 years? So what to do next?

I think if you get into the data log section you will find many over-heat logs. The boiler has a self reset on over temperature condition, until it hits the higher limit setting, then it is a hard lock out, red screen which requires and action to clear.

I'd repipe it. Others might crank the high limit to 200F or so. But that is not a healthy operation logic.

Is the outdoor reset connected? That will keep the boiler running at the lowest temperature, pick up some efficiency also.

Teemok

The cheapest single fix but not the best solution and only fix "might" be a fixed 3 speed Grundfos 26-99 on high and a 3/4 pressure bypass set fairly low so boiler circulation is insured and heat distribution loop circulation minimum is achieved and zone valves aren't forced open.

CraigCO

thank you for everyone’s input