John Carroll

You can check it again tomorrow or sometime when it settles down. Based on the above, the rad output(s) is 0.4*16.666*60*(28.9-20.4)/860, 3.95kW

How many rads in use? and what is/was the boiler flow/return temperature(s).

Very good, on any PP setting, does the Evosta3 show the actual pump head?. (as well as the flowrate & power). I have the Rolls Royce of PP & CP settings on my Wilo Yonos Pico where the settings can be incrementally changed in 0.1M steps to give almost infinite "control" but the head is only displayed while its being changed, no big deal really but nice to have displayed if available.

Where can/do you see the max/min settings for all the 6 PP settings?, the manual only shows the 3 standard PP settings data?. Anyway if you can see it somewhere just change the settings in the spreadsheet.

DAB Evosta-2-3-Installation-and-Operation-Manual_UK.pdfDAB Evosta-2-3-Installation-and-Operation-Manual_UK.pdf The standard (3) PP settings are the ones I'm looking at, you have to press the setting button for 20 secs or so i think to get the advanced (6) PP settings. You can see by my trusty spreadsheet that it looks like PP2 will give a flowrate of 0.4m3/hr ish @ 1.95M Dab Evosta3 PP2.xlsx

Try PP2 which may by my calcs may give a flowrate of just less than 0.4m3/hr at 1.9M.

Voila!!, If not singing Voila, have you checked that the bottom stat works OK in the upper immersion?. "I swapped the thermostat for the one from the upper immersion heater, but that tripped at some time during the night"

Just wondering why a thermostat module that works in the upper immersion should trip due to apparent over temp in the bottom even if the (bottom) heating element is faulty.

Is the hi limit stat part of the control stat or a separate stand alone stat?, whether or which, ensure the (normal) control stat setting is not higher than, say, 70C, normally set to 60/65C, post a photo.

You say the thermostat keeps tripping, do you mean the lower immersion is tripping the RCD (earth leakage trip) or that the hi limit stat is just switching out the immersion and requires resetting?.

A rad(s) flow of 0.5m3/hr, 8.33LPM, with flow/returns of 32C/25C will result in a boiler demand of, 8.33*60*(32-25)/860, 4.06kW, say 4.1kW, if the boiler's minimum output is > this then no cycling, if less, then to increase the rads demand/boiler output means either a greater flow, more noise as higher head required or increasing the flow temperature.

When you say (Evosta3?) speeds 1&2, which mode are you in, both CP2 & PP2 will have similar outputs at both settings but FS (fixed speed) 2 will draw ~ 21W at a flowrate of 0.5m3/hr and will draw 9W closed valve power. The Selectric, if I have the correct pump curves will circulate 0.48m3/hr @ 2.76M speed1, 0.55m3/hr @ 3.63M speed2 and 0.59m3/hr @ 4.18m speed 3, all close if using a evosta benchmark of 0.5m3/hr @ 3.0M. Selectric 5M

What is the exact model of your old Grundfos??. If it is a A rated pump (or not) we can then compare the various modes/settings with the DAB. What model/setting was/is the Dab Evosta3? on to give you 14W, 3.0M, 0.5ms/hr According to its pump curves, the Evosta3 in CP2 (constant pressure) mode will give a flow rate of 0.5m3/h at @ 3.0M head but requires 16W, in CC2 (fixed speed) mode it will only flow 0.2m3/hr @ 14W and also 3.0M, a bit strange.

I have a 2008 Belling 90E cooker which uses MP-V01-SVC simmerstats, original manufacturer, Invensys. These have a relativey short life of ~ 2/2.5 years. I never see any complaints re this short life as this type of simmerstat must be widely used, wonder is this a fairly typical lifespan?, only 2 people in this house. I had a Creeda Cavalier for 20 years or more cooking for a family of 5 with not one simmerstat failure. I opened one (failed) up today, and can see that the PCB eventually wears down where the baynot strip end in the cover contacts it due to the very slight pivoting movement of the 5W heating element/bimetal strip as it opens/closes, (rises/falls) the main contacts, the element will then heat continuously as the 5W heater stops working, until switched off. Most of the cookers I see in Spain don't use this system, the elements have several spirals and are switched in directly by the control switch. Look at the red arrows in the attached, if interested.

Also, check direction of the arrow on the side of this check valve.