Question about NTI FTVN110C Combi Tankless

harry_fine

First post. Far from an expert but I want to understand my new NTI FTVN110C combo boiler system in my new condo.

Developer installed the combi boiler as above. It does domestic hot water and heating through an air handling unit. Heat by gas boiler is a new concept to me. It seems a lot more maintenance is required as opposed to a forced air gas furnace and hot water tank. 

I'm trying to understand some basic concepts. Here's what I think is true. I would appreciate correction.

1. The same boiler heats domestic hot water and the furnace heating water through separate heat exchangers. 

2. The heating side is a closed loop. Water or some water mix was installed at install and doesn't need cleaning or replacement. 

3. The DHW side needs cleaning annually. I only need to use the kit/pump/chemicals/hose on the DHW lines, after isolating pipes running downstream.

So that's what I think I know. Three questions.

1. Does the combustion chamber need to be cleaned annually and if so, is it something a handy guy can do, following the manual and all safety procedures?

2. Why do I have 2 big expansion tanks as part of the system?

3. After flushing and draining the system, will I need to leave the air out and if so, where is that valve?

4. The green pump in the picture, I assume it's the supply water going to the furnace. How is the pressure setting determined?

Ironman

The combi was probably chosen because of space limitations.

1. The heat exchanger should be inspected annually and cleaned as needed. I wouldn’t recommend that you try unless a pro has shown you how to step by step.

2. One expansion tank is for the hydronic side, the other for the domestic.

3. By “Flushing”, I assume you mean chemically descaling the domestic side of the plate heat exchanger. This is not the same as main HX. That requires a pump, hoses, a bucket and solution. Again, I’d recommend having a pro show you how it’s done.

4. I’m not sure whether you mean the static fill pressure on the system or the speed of the pump? Either way, you should not try to adjust these. That’s done at installation and should be left alone if correct.

hot_rod

Im not a huge fan of pex for boiler piping, is it all 3/4”? The zip ties look a but low budget🥴

My thought is to open the boiler for cleaning and recalibration, or at least check the combustion  readings again, after the first season. If it looks clean in the combustion area, you might go two years between cleanings.

Its a good idea to check the fill water. Hardness, ph, tds, maybe chloride levels. The manual has a water quality spec.
Im a proponent of adding a hydronic treatment also. They contain oxygen scavengers , film providers, ph buffers. They protect all the various metals in your system

harry_fine

Its a good idea to check the fill water. Hardness, ph, tds, maybe chloride levels. The manual has a water quality spec.

What control do I have over that. It's city water.

Im a proponent of adding a hydronic treatment also. They contain oxygen scavengers, film providers, ph buffers. They protect all the various metals in your system

How often would you do this sort of treatment? Is it a difficult task treating this closed hydronic system in an NTI boiler?

hot_rod

If you have hard or extremely hard water you can soften it before it feeds the combi, on the domestic side. Or perform a descaling process every few years.Not everyone likes softened water.

The chemical cleaners and inhibitors come in aerosol cans that you inject into the system. If it was never cleaned on the boiler side, run a cleaner for a few days, flush, refill and add the conditioner

Tom_133

there are several red flags on that install. Someone put a circulator on the supply but there is one inside that boiler. Not sure how your zones are piped, but that may cause some flow issues. I dont know what your local code is with pex being that close to your boiler, but here in vt I think you need 6' of copper before you go to pex. I didnt see a way to extract air on that system from the pic either. Not trying to make you nervous, but I dont like the workmanship

GGross

I sure hope you didn't pay someone money to install this

dko

I'm upset just looking at it

psb75

Very unprofessional. Installer was big fan of Uponor fittings.d