Descaling a gas water heater

[galeus]

I have a Rinnai gas water heater which is an excellent bit of kit which powers our shower as well as the sink. For the last year the water flow has been getting worse with a lot of squeaking coming from the heat exchanger area. I know there is a bloke on ebay who will sell you an exchange boiler core, but has anybody tried rigging up some sort of descaling process, without dismantling the boiler itself. I'm thinking if say Kilrok or similar was introduced/ fed into the cold water feed to the Jabsco pump and run through sufficiently to leave in the boiler for a period, perhaps.

 

[Boater Sam]

Use citric acid powder, non toxic and easily washed out.

It may only be the inlet regulator that is limed up, that reduces the flow and causes kettling noise.

 

[Mudisox]

I have 2 paloma water heaters. When needed I remove them from the 3 pipes at the bottom, having turned the water pump and gas pipe off. invert it and fill with oxalic acid for 24hrs+the flush through. Also work the heat control valve backwards and forwards.

Job done.

Paloma Bob can also be your friend in need.