Can I manage without Mixer Valves

[JonJump]

I am very interested in the views of the knowledgeable people here, because I am very excited about this project, but mistakes are expensive.  I am engaged on renovation  (although it's basically a rebuild apart from the slab).

Any advice/opinions gratefully received, and in particular

- do I NEED mixer valves if I can set boiler flow to 50 and use a motorised valve?

- can I get away with ambient sensors, and not have to embed some in the floor itself?

- since I am computer controlling, I can easily arrange it so the boiler only runs if one of the MVs is open.   But belt and braces, the Bathroom towel rail is a bypass loop IF I OMIT the TRV.   Do I need to do that?

 

Thanks, peeps - really look forward to hearing from you.

 

OTHER INFO

 

-   total floor area ~ 180 sq metres, and insulation will be to at least latest building regs.

- retaining existing 24Kw condensing combi with built-in bypass valve

- MVHR system

- 4 zones UFH, + Bathroom Towel Rails + (possibly) 2/3 rads

- computer controlled (I have the skills to do the software and  electrical part of that)

- floor coverings vinyl/carpet/engineered wood.

 

The idea of Mixer Valves in inconvenient places gives me the vapours ... ideally, I want everything in the plant room with the boiler.  So here's my plan...

 

1.  Set the Combi flow temp to 50 (hoorah - we'll be condensing and save gas)

2.  Use 2 port Motorised Valves (computer controlled) for UFH zones (all in the plant room) - increased pipe lengths but simpler and neater

3.  Simple unswitched (no MV) zone to bathroom towel rail with TRV

3.  Ambient temperature sensor in each Zone

 

 

 

 

[PeterW]

33 minutes ago, JonJump said:

do I NEED mixer valves if I can set boiler flow to 50 and use a motorised valve?

Yes as 50°C is too high for UFH

 

33 minutes ago, JonJump said:

can I get away with ambient sensors, and not have to embed some in the floor itself?

Yes

 

34 minutes ago, JonJump said:

since I am computer controlling, I can easily arrange it so the boiler only runs if one of the MVs is open.

Most controllers do that now - use the self balancing actuators from Salus and save yourself a lot of issues. 
 

35 minutes ago, JonJump said:

Set the Combi flow temp to 50 (hoorah - we'll be condensing and save gas)

No you won’t as condensing is a function of return and flow not just flow temperature. 
 

35 minutes ago, JonJump said:

Use 2 port Motorised Valves (computer controlled) for UFH zones (all in the plant room) - increased pipe lengths but simpler and neater

Expensive and pointless - use a manifold and actuators. 
 

36 minutes ago, JonJump said:

Simple unswitched (no MV) zone to bathroom towel rail with TRV

What happens when TRV closes and blocks the flow while the pump is running ..?? 

[JonJump]

Peter - thanks for the response ....

 

2 hours ago, PeterW said:

3 hours ago, JonJump said:

do I NEED mixer valves if I can set boiler flow to 50 and use a motorised valve?

Yes as 50°C is too high for UFH

• Interesting - what flow temp would be OK?

2 hours ago, PeterW said:

3 hours ago, JonJump said:

can I get away with ambient sensors, and not have to embed some in the floor itself?

Yes

Cool - no issues with lag?   Expect UFH above 120mm insulation, then vinyl or carpet

 

2 hours ago, PeterW said:

3 hours ago, JonJump said:

since I am computer controlling, I can easily arrange it so the boiler only runs if one of the MVs is open.

Most controllers do that now - use the self balancing actuators from Salus and save yourself a lot of issues. 

Those look interesting.   Thanks

 

2 hours ago, PeterW said:

3 hours ago, JonJump said:

Set the Combi flow temp to 50 (hoorah - we'll be condensing and save gas)

No you won’t as condensing is a function of return and flow not just flow temperature

I see your point.   So it's actually a function of load/demand i.e. which parts of the system are actually live, and thus increasing the diff between flow/return.   Hadn't spotted that.

 

2 hours ago, PeterW said:

3 hours ago, JonJump said:

Use 2 port Motorised Valves (computer controlled) for UFH zones (all in the plant room) - increased pipe lengths but simpler and neater

Expensive and pointless - use a manifold and actuators. 

Very possible - I clearly need to spend a bit more time understanding actuators.   

 

2 hours ago, PeterW said:

3 hours ago, JonJump said:

Simple unswitched (no MV) zone to bathroom towel rail with TRV

What happens when TRV closes and blocks the flow while the pump is running ..?? 

Is that not what the bypass in the combi is for?