I have a alex 2 running off a flojet and my line pressure shows at 3.5 to 4 bars when idle. when I pull a shot bar bounces between 10 to 10.5 bars untill my flow starts and then stabilizes at 10 bar.(alex 2 and duetto come preset at 10.5 ) due to the bouncing pressure will it effect my shot since it stabilizes when the flow starts? If it does what size accumulator tank is suggested? also what pressure are other alex 2 and duetto owners finding the best bar pressure for them is? I tried 9 bar but seemed to low for this machine, could have been inaccurate reading on gauge.

TY for the help Erics would this tank work since the flojet is 40 psi max : Watts 2.1 Gallon Hydronic Expansion Tank -Maximum pressure 60psi (4.1 bar) . will I need anything else other than a T valve and regulator ?

Thanks again for the help. I think I have everything finally.I dry fit everything and will hook it all together tomorrow. I wanted to see if I missed anything. I found a utilitech 2 gallon diaphragm well tank pre charged to 20 psi. 100 psi max.(taking your advice),a watts pressure regulator and a 100 psi gauge. not sure about adding a relief valve? will I need one? Also it says tank pressure must be set 2 psi lower than pump cut on pressure . does anyone know what the cut on pressure would be on the flojet bw 4000A. only info I found is the flow rate which is 1.1gpm (4.1 Lpm). I know the bar conversion for regulator is 29.0076 psi = 2 bar going in to my machine . heres some pics. did I miss anything?

Couple quick notes. 1 a pressure gauge should always be sized to read the intended working pressure at mid range. Anything else stresses the internal springs and will not reveal pressure changes adequately. Such as line drop when inlet valve opens or water hammer when some other valve closes. Water hammer is the result of water flowing at speed down a pipe/hallway and the door gets slammed shut. The water hits the door with the kinetic energy of the weight of the water, not pressure energy, until it stops moving . 2 your brewer is looking for stability in line pressure AND flow rate, nothing else will provide a consistent brew. When a mfg claims the unit is rated for 20-90psi all he is saying is it will work. He makes no claim that the brew will taste the same this morning at 30 psi and tonight at 75psi. Funny thing, all line pressure drops in the morning, because of toilets and showers. Watch your gauge at half time for the superbowl. I have seen near zero in a high-rise. An expansion tank's purpose is to provide water volume back into the feed line when and only when line draw, Ie flow rate, exceeds the ability of the incoming line to maintain an even RATE. An unlikely situation for an espresso brewer. More likely for a coffee brewer trying to refill a holding tank during a 3.5 minute, 1/2 gallon brew. An expansion tank is not intended to preserve pressure as the air bladder inside deflates as it gives up its water. It mellows rapid psi changes but its not designed to maintain it. Ala the 2psi below incoming line pressure allows the bladder to compress thus allowing water Volume to enter the tank. It is this volume that is returned to the feed line should the incoming line fall short. A short fall like this happens momentarily when the connected appliance opens its inlet valve. Keep in mind that without another device such as check valve or regulator up stream of the tank, the return volume and its minor pressure component will move in the path of least resistance, ie back into the building. 3 point. Beware of plastic house type fittings with line pressures above 40 psi. Some are rated for less and some for more. Regardless, they are still hydroscopic and become dry and brittle faster at the high ends of there ratings.

evidently you dont understand the purpose of using a flojet with a accumulator tank pumping from a 5 gallon water bottle. I can hear the toilet flush but dont think it will effect my line pressure

Thanks again for helping. I bought it from lowes (It's the one they recommended) make and model is watts 3/4 N45BU M1 http://www.watts.com/pages/_products_de...p?pid=3429
so I dont have to worry about the tank pressure only being 2 psi lower than the pump cut on pressure ?