Mixing Pressure Problems

[Brambles]

You have too many UFH circuits to feed to have any chance of an unconventional system to work well - unless you know exactly what you are doing. The UFH circuits take a high percentage of the boiler output - they need to be fed directly from the boiler - with the radiator and Dhw circuit in parallel.

The concept of using pumps for “injection” on low temperature heating systems is common in the world of thermal stores, but you need temperature sensors properly located and a control system to drive the pump. From what I can see on your photos, the pump you refer to as an injector is not plumbed in correctly and does not appear to have a temperature control loop or a limiting device to set or limit the flow temperature into the UFH loops. You don’t want 60 plus degree boiler flow temperatures entering the UFH loops.

On a system such as yours, the feed for the UFH circulation should come direct from the boiler to a pumped manifold with a mixing valve - relatively cheap and it will work.

If you had one or two UFH loops you may get it to work in an uncontrolled manner by tweeking it.

 

[Savdefriz]

You have too many UFH circuits to feed to have any chance of an unconventional system to work well - unless you know exactly what you are doing. The UFH circuits take a high percentage of the boiler output - they need to be fed directly from the boiler - with the radiator and Dhw circuit in parallel.

The concept of using pumps for “injection” on low temperature heating systems is common in the world of thermal stores, but you need temperature sensors properly located and a control system to drive the pump. From what I can see on your photos, the pump you refer to as an injector is not plumbed in correctly and does not appear to have a temperature control loop or a limiting device to set or limit the flow temperature into the UFH loops. You don’t want 60 plus degree boiler flow temperatures entering the UFH loops.

On a system such as yours, the feed for the UFH circulation should come direct from the boiler to a pumped manifold with a mixing valve - relatively cheap and it will work.

If you had one or two UFH loops you may get it to work in an uncontrolled manner by tweeking it.

The system does have thermocouples and a control system. There is a temperature sensor for the boiler feed, and a temperature sensor for the mix. The injection pump is supposedly controlled by the processing unit to control the flow of water into the UFH system so that the temperature of the mix is appropriate to the outdoor conditions (which is measured by a third thermocouple on the north facing wall). It's just that the pressure on the UFH is hard to balance and I don't know enough about a Grundfos Alpha 2L to know what I'm doing!
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The system does have thermocouples and a control system. There is a temperature sensor for the boiler feed, and a temperature sensor for the mix. The injection pump is supposedly controlled by the processing unit to control the flow of water into the UFH system so that the temperature of the mix is appropriate to the outdoor conditions (which is measured by a third thermocouple on the north facing wall). It's just that the pressure on the UFH is hard to balance and I don't know enough about a Grundfos Alpha 2L to know what I'm doing!

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The system does have thermocouples and a control system. There is a temperature sensor for the boiler feed, and a temperature sensor for the mix. The injection pump is supposedly controlled by the processing unit to control the flow of water into the UFH system so that the temperature of the mix is appropriate to the outdoor conditions (which is measured by a third thermocouple on the north facing wall). It's just that the pressure on the UFH is hard to balance and I don't know enough about a Grundfos Alpha 2L to know what I'm doing!
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The bluebox on the wall is a kanmor 361e controller.

 

[Brambles]

I am very familiar with Kanmor and the 361 - it does not (nor is it intended) to control the UFH flow temperature. For that you need a wax operated mixing valve.

The Kanmor 361 is intended to inject hot water from a controlled (known temperature balanced source ( plus or minus 8 degrees )) - and that is a thermal store not a direct fired boiler. The Kanmor has no capability to accept a return temperature so cannot adjust to any feedback from a fluctuating flow temperature.

The external temperature sensor feeds directly to the boiler and adjusts the flow temperature against a preset curve ( which you can adjust) - it has nothing to do with the performance on the UFH - it only adjusts the boiler flow temperature, it does not adjust mix - it has no control loop to do that.
It operates on what is known as proportional bounded adjustment - it takes the feed temperature and then applies a preset reduction to feed the UFH

Be very careful with an UFH if you have expensive floor coverings - you don’t need many (upward) temperature excursions to cause damage to engineered wood or fabric covered floors

 

[John.g]

What is the temperature now??.

 

[Savdefriz]

I'll bow to your greater knowledge, but my system does look like the one that I found in the manual.

tekmar 361 Mixing Control - Manual (Page 4) - https://www.manualsdir.com/manuals/594646/tekmar-361-mixing-control.html?page=4

Temp has dipped to 30 at the mo but not too worried as DHW has just been on for kids baths. The house feels a bit better, but there's a lot of concrete that needs heating so I'm not expecting to see any significant rises for days (if I'm lucky enough to get any at all)

 

[Brambles]

I will say no more. Look at the schematic on page 1 of the manual on the link you have posted.

That is not the system you have shown in your photos. Also note the inputs ( 3 no to the controller) and then reread my earlier posting

 

[John.g]

can you just feel the pipe just to the left of the T for the injection pump, it should be very hot....at boiler temperature, now feel the pipe on the inlet to the inj pump.....that too should be at the same temperature, if not and only lukewarm (30C) then you are simply pulling in cold water from the by pass and the system will never work, you have a good chance if you break the flow/return loop.

 

[Savdefriz]

I will say no more. Look at the schematic on page 1 of the manual on the link you have posted.

That is not the system you have shown in your photos. Also note the inputs ( 3 no to the controller) and then reread my earlier posting

I don't know enough about this stuff but I'm learning. Here's the schematic of my system from the book. (Although I've no radiators). As I said I'm just a science teacher trying to warm up his house.
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can you just feel the pipe just to the left of the T for the injection pump, it should be very hot....at boiler temperature, now feel the pipe on the inlet to the inj pump...that too should be at the same temperature, if not and only lukewarm (30C) then you are simply pulling in cold water from the by pass and the system will never work, you have a good chance if you break the flow/return loop.

Pipe to the left is hot, injector pipe is hot, pipe to the right is hot but cools once it gets to the relay. Pump is hot and temp is rising again.
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can you just feel the pipe just to the left of the T for the injection pump, it should be very hot....at boiler temperature, now feel the pipe on the inlet to the inj pump...that too should be at the same temperature, if not and only lukewarm (30C) then you are simply pulling in cold water from the by pass and the system will never work, you have a good chance if you break the flow/return loop.

Pipe to the left is hot, injector pipe is hot, pipe to the right is hot but cools once it gets to the relay. Pump is hot and temp is rising again. I've got pump set to lowest setting which seems to help.
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I don't know enough about this stuff but I'm learning. Here's the schematic of my system from the book. (Although I've no radiators). As I said I'm just a science teacher trying to warm up his house.
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Pipe to the left is hot, injector pipe is hot, pipe to the right is hot but cools once it gets to the relay. Pump is hot and temp is rising again.
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Pipe to the left is hot, injector pipe is hot, pipe to the right is hot but cools once it gets to the relay. Pump is hot and temp is rising again. I've got pump set to lowest setting which seems to help.

Even the pipe directly under the pump feels hot..... Oooohhhh such excitement

 

[John.g]

Didn't realize you had no rads so if no demand for HW then is the boiler running constantly now or cycling on/off?.

 

[Savdefriz]

Didn't realize you had no rads so if no demand for HW then is the boiler running constantly now or cycling on/off?.

Cycling. It seems to kick in to push the temp up then falls back. I think it's kicking in when the boiler temp sensor falls below about 52. It pushes it up to about 72 and switches off.
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Cycling. It seems to kick in to push the temp up then falls back. I think it's kicking in when the boiler temp sensor falls below about 52. It pushes it up to about 72 and switches off.

Now it seems to be constant..... I need to spend less time with my boiler and more with my wife!