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Discuss Mixing Pressure Problems in the Central Heating Forum area at PlumbersForums.net

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30
I think the Kanmor box is supposed to control the pump that injects water. The bypass valve I believe is supposed to be passive as its job is essentially just to allow a flow back equal to the amount of water injected and that's how the water returns back to the primary system.

I thought that I might be able to play about with the pump settings and valve and coax the hot water round but there are too many variables for me to play with.

Cheers for the help though, I've often been told that the system I have is a bit different!
 
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As John ,g has said never going to work!
I would just go for sorting it properly by fitting a pump/ blender unit to each manifold each feed by a dedicated zone valve. Get rid of current underfloor pump if the one shown is only bypass on system change it for a auto bypass .
On the picture of the manifold all the actuator heads have been removed I take it they do work?
 
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There's a bit of a delay as my posts seem to take an age to get through moderation (probably because I'm new). The actuators have been taken off to make sure that I was getting flow everywhere. The Alpha 2L injector is supposed to be controlled by the Kanmor 361 controller box. I've fiddled with it again and managed to persuade a little hot water to come down through the pipe to the injector, but I was hoping that swapping the bypass valve to an auto bypass might have been the answer, looks like it might be a bit more costly!!
 
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Yes I'm afraid some cost involved but it's not much use as it is!
Correctly working ufh is lovely to live with .
Make sure you get a heating engineer who is familiar with ufh both pipework and its correct wireing.
 
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No it's not much use as it is at all. The problem is that the bloke who built the house used non standard parts for everything, from the boiler to the manifolds. I've just had a good read of the pack and need to change some settings on the mixer controls... You never know, it can't do any harm!
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I think I've got it sussed. Checked the system and there are 2, 2 zone part valves going to the DHW and primary loop. When the system calls for DHW the boiler loop loses pressure and the cold water from the UFH pushes back into the primary loop via the bypass. When the valve opens to supply hot water back to the primary loop, the hot water struggles to overcome the pressure of the cold water coming back through the bypass and can't reach the injector pump. If I play with restricting the manual valve I can usually resume the flow of hot water to the injector but it's very sensitive. I think If I replace the manual valve with an auto valve and then rebalance it might solve the problem..... Well here's hoping (and I hope that all makes sense as I'm a science teacher and not a heating engineer and before Monday knew nothing at all about UFH systems!).
 
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Despite our reservations, it is certainly a very interesting challenge. logically, one would think that it should work in some fashion or other, if not perfectly, some design guru went to the trouble of putting this package together with the Kanmor 361 and the injection pump etc, if you have any links to its setting up you might post them.
Re the injection pump control which is one of the key components, the speed/frequency is controlled by the Kanmor but this is only designed for the older type of circ pumps (see quote) some of the newer types can be externally controlled, but only by a PCM (pulse width modulation) signal which is plugged into the pump motor. I wonder was your injection pump changed out sometime for the present Alpha 2L which cannot be speed controlled IMO by the Kenmor.

Quote:
HVAC Systems
The Mixing Control 361 is designed to operate a mixing pump using Outdoor Temperature Reset. It can be used in applications ranging from in-floor radiant to commercial baseboard systems for Boiler Return Protection with full reset. This control regulates a single heating water temperature through Mixing Outdoor Reset. It provides mixing by speeding up or slowing down a single permanent capacitor (standard wet rotor) circulator, and provides control of the mix system pump. Unquote.
 
Messages
30
Despite our reservations, it is certainly a very interesting challenge. logically, one would think that it should work in some fashion or other, if not perfectly, some design guru went to the trouble of putting this package together with the Kanmor 361 and the injection pump etc, if you have any links to its setting up you might post them.
Re the injection pump control which is one of the key components, the speed/frequency is controlled by the Kanmor but this is only designed for the older type of circ pumps (see quote) some of the newer types can be externally controlled, but only by a PCM (pulse width modulation) signal which is plugged into the pump motor. I wonder was your injection pump changed out sometime for the present Alpha 2L which cannot be speed controlled IMO by the Kenmor.
Indeed it was...... I'm off to work, but I'll post settings when I get home.
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Despite our reservations, it is certainly a very interesting challenge. logically, one would think that it should work in some fashion or other, if not perfectly, some design guru went to the trouble of putting this package together with the Kanmor 361 and the injection pump etc, if you have any links to its setting up you might post them.
Re the injection pump control which is one of the key components, the speed/frequency is controlled by the Kanmor but this is only designed for the older type of circ pumps (see quote) some of the newer types can be externally controlled, but only by a PCM (pulse width modulation) signal which is plugged into the pump motor. I wonder was your injection pump changed out sometime for the present Alpha 2L which cannot be speed controlled IMO by the Kenmor.

Quote:
HVAC Systems
The Mixing Control 361 is designed to operate a mixing pump using Outdoor Temperature Reset. It can be used in applications ranging from in-floor radiant to commercial baseboard systems for Boiler Return Protection with full reset. This control regulates a single heating water temperature through Mixing Outdoor Reset. It provides mixing by speeding up or slowing down a single permanent capacitor (standard wet rotor) circulator, and provides control of the mix system pump. Unquote.
Add
Indeed it was.... I'm off to work, but I'll post settings when I get home.
I've got the full plumber/electrician pack with all the settings. We might get this thing figured out eventually. John you seem to know a lot about the pumps (of which I know nothing), do you think that maybe changing the Alpha's setting might help in the short term?
 
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It may but last night I was looking at the system schematic and can't figure out why the injection pump inlet is taken from the boiler return (NRV in boiler flow), this means that if no demand for DHW or radiators that the injection pump, is fighting the boiler circ pump (which is on the return), very UNlikely designed that way, have another good look at the arrow on the injection pump which may be pointing upwards, the pump would then be returning cold water to the boiler but then there would need to be (probably controlled ) a hot water supply to the UFH main manifold somewhere, if you look at the schematic which includes the DHW cylinder you will see some form of controller that looks a bit like a pump but is probably a controller as it seems to be wired into the kanmor? high up in the drawing, can you identify this as well this evening.
 

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Right then John what do you want? IMG_20201130_165133.jpg
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The only thing missing from the schematic is the outdoor sensor which I think that the unit uses to calculate the flow need to keep the house at a certain temperature. I've also changed the alpha pump settings to lowest constant flow (I) and that seems to be letting the hot water flow through from the primary circuit.

As for the flow, here's my hypothesis:

The primary circuit has two junctions, the first is the intake and the second the return flow. I'm assuming that if the pressure of the return flow is greater than that of the primary the hot water will take the path of least resistance and flow downwards to the injector pump. This seems to be what's happening in practise, as if the return flow is too fast the hot water never gets to the t junction. If it's too slow, the injector doesn't allow any water to be injected which could be due to the incompressible nature of the ufh circuit, or just because the path of least resistance is forwards rather than down.... (I need a degree in fluid dynamics for this one!)
 
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Arrow is definitely pointing down. Pages as requested, but I don't know what I've done but the mix temperature is going up. It's at 27 now and rising and it's never been above 21. Basically I put the alpha on (I) waited until primary was sending warm back to the boiler, changed to the pump up to highest constant and it seems like it's working 🤯
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Just checked again and it's back to 24 but progress.... I suppose it's proof of concept at least.
 

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