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If this boiler is being cold fired, and you want to continue to do this, then you will have to delay the heating of dhw until the boiler is hot enough to make hot water, not rob fronm your inndirect.
You may have to replace the aquastat on the boiler, with a triple aquastat, and adjust the min. boiler temp a little higher, so the boiler can respond fast enough.
I don't believe it sounds like your boiler is designed to be a cold start boiler. Running it like this does not make it one. It has to have controls on it to make it work right.
Would advise running this boiler whatever why it was designed to run, or adding controls to make it work right.
You are saving nothing in fuel in the long run, if your boiler is scaling up and running poorly.
I only hope your heat zones are all high temp, and you are not trying to run this boiler for radiant floor heat, directly off the boiler, w/ no mixdown.