Offer for heating / sanitary / ventilation - is it realistic?

Bookstar is right, though.
Last year we built with openly tendered individual trades and had at least 3 offers for each trade.
Differences between 1 and 15 percent are possible but 30 percent for the same tender, well. It has nothing to do with envy.
And they are all busy, believe me.
Better check the company in the [Bundesanzeiger].

So thank you for your comments but you don't need to worry about my heating engineer. Unlike me, he wouldn't have to work anymore.

What rather speaks even more for something being wrong or not comparable. But everything has now been said from my side, I just didn’t want you to give the colleague false hopes.

Simply do not make any advance payment and that's fine. Payment will be settled at the end. Treat yourself and also wishing you great success.

Simply do not pay in advance and that's that. The bill will be settled in the end. Treat yourself and good luck

Thank you very much! The heating engineer will start at the end of August – if he comes.

I'm keeping my fingers crossed.