Time to prime?

[Kit_L]

I have a TMC 24v Motor and Macerator fitted to my toilet, which is raw water fed, and I have a new spare standing by. I am debating as to when to change the new for old. The current works well, but it is slow to prime. The setup:

How many seconds is acceptable priming time between pressing 'Flush: button to when water appears in the bowl to clean and flush? The vertical distance between the raw water level in the supply line to the clear inlet pipe that feeds the pump/macerator is about 2' (600mm). There is no non-return valve in this line; one could be fitted.

Peggy, I bought your book the day before yesterday, so have a better understanding of theses systems than I did, but I am not sure that this question was answered. I also do not know how many years it's been since this unit has been serviced, so I assume the possible culprit is the joker valve (we have full power to the toilet). This is the reason I bought the motor as well as all the service parts in a single kit, which I obtained for a very reasonable price. When I change it, it will literally be an hour's work.

And since buying your book I do prime the bowl with a large cup of water before pressing the 'Go' button.

So, how long is too long? I just tested this now, and it's 17" before appearing from the top of the bowel. TIA, KL

[Kit_L]

Peggy must not have seen this (I see she's been busy over at TF), so I will update here.

I decided to tackle this job, having decided I had put this off for too long. The changeover of the full single kit (not a service kit, where all replaceable parts have to be exchanged, but a fully assembled motor and all-moving-parts kit) went pretty smoothly.

As soon as I pulled the delivery hose off (lots of very hot water, and muscle power) instantly I saw there was no joker valve. So, that answers the 'time to prime' question. The replacement kit was different in a number of ways (I expected this) but the main holes lined up. I did need to heavily modify a socket to be able to tighten the coach screws that hold the bottom flange to the sole.

A cup of water in the bowl, and a second or two to prime now. All working as hoped for.