Descale combi boiler

raricky

Hi guys

I have a combi boiler unit (IBC199 + IBC hydronic furnace) . Last week I attempted to descale the boiler side after watching some youtube videos assuming its going to be pretty straight forward. But after turning on the submersible pump nothing came out from hot water side of the heater. So I called a local plumber and he advised I need isolation valves kit installed on our boiler to get this done, as there are only drain valves present. Then I checked with the company which originally installed this system and they gave me a enormous quote of like 1000$ to descale both boiler and furnace. This is quite expensive for me.
And they also said no Isolation valves are needed to clean the boiler and they will do the cleaning without them.

Is there really a way to clean boiler without isolating it ? Attaching some pics for reference

TIA

hot_rod

Well tankless valves certainly make it easier, if you plan on doing it yearly.

Are you capable of installing these yourself? Then the kit is super simple to use.

raricky

@hot_rod Yeah, its really simple with these valves to clean the unit.
Since we live in a townhouse and one of their bylaws states any plumbing modification work needs to be completed by a certified contractor.
I am probably going to call a professional to get this done, if these valves are the only solution.
Thanks

GGross

you do not descale the boiler side, you can descale the domestic side, they do not cross water pathways. It is ideal to leave the boiler fluid alone, adding more water adds more minerals. Most combi flat plates don't scale up like a tankless water heater, cleaning the domestic side only shouldn't hurt anything though

raricky

@GGross I don't think I can even Descale tankless water heater without isolation valves.

kcopp

For Starters this is an IBC SFT199 tankless water heater…. its not a combi boiler.

Note that there is only 1 hot and 1 cold.

The IBC SFC combi boiler has separate ports for heating and domestic.

How old is the install and how hard is your water?

hot_rod

https://forum.heatinghelp.com/discussion/comment/1854816#Comment_1854816

Or is it a combined system DHW and radiant?

kcopp

Im sure it being used for both… Note the Non-barrier pex tubing.

What is the circ pump? Hopefully it a SSS or bronze set up…

I realize that these are "approved " set ups but I am still not a fan..

We would need more pix further back.

mattmia2

I don't really even see a cost advantage over a gas furnace and tankless water heater.

raricky

@kcopp You are right! This is used for both heating and domestic water.
There is a circulation pump which I believe pumps hot water to the hydronic furnace.
Also there is a cold return water pipe from the furnace which goes back to the tankless water heater.
Attaching a pic from the other side of the tankless heater

And there is a valve outlet on the furnace side , not sure of its purpose

raricky

@kcopp The unit was built in 2021. Water here has a high mineral content.

kcopp

Now that I see there are 2 boiler drains and there also must be at least 1 shut off you may be able to use them to circulate an approved descaling fluid through the WH and the Air handler coil.

Not the most effective set up but it could very well work…

raricky

@kcopp So this is what I did. Turned off both the boiler drains and connected a hose to each of those.
Cold water side drain was connected to submersible pump and hot side hose was left in the bucket. After turning on the pump nothing came out from hot water side drain of the tankless heater.
Not sure if I am missing something in this process.