Issue with radiant zones

the pumps associated with the problematic zones are sufficient when the other zone pumps aren’t running, though? Could it be that you’re not getting enough volume of water to the manifold and for multiple zones to heat simultaneously ?

It looks like some one reduced the piping feeding the existing manifold or at least it seems so being i see a press fitting attached some older soldered fittings.If you operate your trouble non heating zones alone and they work then i would conclude that some one who had repiped it made a mistake . What type of tubing was used pex , rubber and what are the radiant zones in concrete or plates and staple up being i see no mixing valves unless the home is all radiant and the boiler is programed for such operation . I would gather that the boiler was replaced recently and that the issue never happened w the old boiler and piping and pumps ? If the ghost flows and need for the check valves where only needed later then i would say some body screwed up and most likely are clueless when it comes to basic hydronic piping . I see a Grundfos 15-58 is that piped feeding or attached to your radiant manifold if so that may be part of the ghost flow and need to add check valves . Also where the pumps changed due to heating issue as to fix which it did none of? i think you may have the wrong guys working on your system it happens every body knows all until they don't know but they charge for there mistakes and learning on your dime . Also those pumps look like bronze body extra$ which if not a open system is a total waste of money . In closing i see some soldered stuff and then some press i would the press guy changed /repiped something and screwed it up or possibly it been wrong forever and working possibly not as well as it should be . I would say the quality of the work does not appear to be a show case being when i ve done radiant i would make sure that everything was beautiful and functioning and basic pipe sizing gpm where adequate for the load . Not bashing just putting it out there .

peace and good luck clammy

Just notice all those pumps are union style,this is far and few between in my neck of the woods .I didn't even know b&g made pump w them for the us market pretty sure there extremely common in europe . Is this residents in the united states or canada ?

clammy

Just fwiw usually mod con are piped primary secondary using 2 closely spaced tees or as most do a hydroseparator which none of which i see which just about any body installing mod con correctly would not install without using so to cut to the chase who ever installed needs to place the tools down and chose another profession . Also stating that your portable water had to be separated from your heating system is some thing in my part of the woods no one would think of doing w out be sued and the one or two set up i ve seen where all by home owner diy and worked horribly and cost a fortune to operate and work terrible . i could see some using a tankless water heater and trying to get it to work but they never do it to well . I think i would toss those b n g pumps install some grundfos 15.58 pump w checks for starters and get some one who truly knows hydronics to be repiped.While operating the heatings zones ae you getting thermal migration from the domestic hw tank ? Business is quite savage and most never have a idea of whether there getting ripped or even if the guy has a clue really rough out there . I personally do not claim nor ever to be the worlds best mechanic but it dont take being one to see that your install was sub par lacking really proper planning and execution ,it may work w issues but most professional installed system do not have these issues .It s the one installed by the rule of thumb and low ball pricing that are full of issue some which can not be straighten out because money was saved for other things in the home that seemed more important . The pic of your system is basically why i dont even bother trying to sell radiant to the people because done properly its costs alot $ so i dont argue and haggle i let some one else do it for way cheaper and usually it works like crap also being older and on the final end of a given life span why would i waste my time even figuring it out being they will not like the price and i certainly am not working for free . Radiant done properly isn t just in the boiler room thats the cheapest area even going top of the line its all the other stuff like tubing lay out surface contact the r valve of flooring and insulation and box and end beam closure and manifolds .all this is whats the most important and usually hand off to some one else that say it does not matter . Being you seem to have light style plates and larger tubing for the staple up is a issue to me being those types of system usually have to operate at a high temps to work properly plus there the cheapest type of fly by night not real radiant usually installed for about 1/3 the price of a real plate system and the plate system operate at a much lower temps and lower fuel usage . None of this is a rant just a clear expression of what really goes on out there and what some call a professional install done by some without a clue ,this is a reason why hydronics and radiant is such a small section of the heating industry and getting smaller . Sad to see that real pride and quality done by peopel is crap . This why some don t even bother because how do price against some one who really does not care about what they do or is it that they just don t know and are following what some one told them to do clearly they get paid . sorry state of the heating industry peace and good luck clammy