Lazy Water - Zones Not Working Help

[Andycap836]

Hi Guys,

Appreciate any help I can get.

We have an old house which was totally renovated & upgraded 15 years ago.

There is a control panel in the utility room which controls the heating/water. It has 3 buttons:
Zone 1) Ground Floor - underfloor heating with 3 individual thermostats (no idea why as the area is small enough but it is what it is)
Zone 2) First floor and 2nd Floor - radiators with one thermostat on each floor - I presume the 2 thermostats splits Zone 2 into Zone 2a and Zone 2b.
Zone 3) Hot water tank

We cannot run Zone 1 & 2 at the same time i.e. the radiators on 1st & 2nd Floor won't heat if the Ground Floor heating is on. Hot Water tank seems to heat no mater what radiator/underfloor is on.

The boiler is in a return utility room halfway between the ground floor and the 1st floor.

The plumber who installed a new boiler for us in 2019 (when we bought the house the old one didn't work) says the problem is lazy water i.e. when the valves are open for all floors the hot water will go the easiest route i.e. down to heat the underfloor heating on the Ground Floor rather than travel up to heat the 1st & 2nd Floot.

The boiler is a volkera Mynute 35HE 34KW and the plumbers solution is to add a pump on the 1st & 2nd floor heating pipes which goes on when we turn on the Zone 2 heating.

I've been reading a little about this, and it seems the heating is pumped by a pump within the boiler. If we upgraded the pump within the boiler would this work?

Or does none of the above make any sense and I'm totally wrong?

I'd appreciate any advice at all.

Thanks
Andy

 

[Gasmk1]

you won't be able to upgrade the pump within the boiler as it is a 15/60 grundfos head but the body is made for the boiler so you are stuck with it you could try balancing the system to force the water around the systems better. there should be a pump on the underfloor manifold so the boiler pump should be adequate

 

[SJB060685]

Has this been a problem from the beginning?

 

[Andycap836]

Has this been a problem from the beginning?

It has been a problem since we bought the house in late 2018 and our new boiler was installed.
I've no idea if it was a problem for the previous owner and the boiler they used.

Given I can't upgrade the pump inside the boiler (per Gasmk1 above), would a more powerful boiler with a strong pump solve the problem?

 

[SJB060685]

Initially I think this is a flow rate problem, although I could be wrong. It would help if you had an idea of each circuit load requirements (kw required)
I think the fix will be hydronically separating the system at the boiler, adding additional pumps in series will cause complications further.

 

[Andycap836]

Initially I think this is a flow rate problem, although I could be wrong. It would help if you had an idea of each circuit load requirements (kw required)
I think the fix will be hydronically separating the system at the boiler, adding additional pumps in series will cause complications further.

By hydronically separating do you mean have two pipes coming out of the boiler, 1 feeding the upstairs and 1 feeding the downstairs, rather than one pipe coming out now which then splits into 2 pipes (1 for upstairs and 1 for downstairs)?

Flow rate, circuit load etc are all way above my head. I have no plumbing skills.

 

[SJB060685]

By hydronic separation i mean separating circuits from each other, allowing additional pumps to be used that won't interfere with each other. If your plumber was to install an additional pump as you mentioned above this is likely to cause interaction between the new pump and the boiler pump, potentially robbing the ground floor circuit of heat.

 

[Andycap836]

By hydronic separation i mean separating circuits from each other, allowing additional pumps to be used that won't interfere with each other. If your plumber was to install an additional pump as you mentioned above this is likely to cause interaction between the new pump and the boiler pump, potentially robbing the ground floor circuit of heat.

I was possibly thinking something similar to what you're saying.

When the plumber suggested another pump, I thought that there's going to be a pump in the boiler pumping the heated water, then there's going to be another pump outside only servicing the upper levels - would this not suck all the hot water upstairs and deprive the downstairs level of it?

Gasmk1 in his post above assumed that our underfloor heating would have it's own pump. I had a look at it and it seems it doesn't - Pic attached. From google images of underfloor manifold pumps it seems they sit between the two horizontal bars on the left hand side - there isn't one on this one. Would this be causing a problem?

 

[SJB060685]

Is there even a mixing valve on or next to that manifold connected to the pipes? Does the UFH serve all of the ground floor?
A pump as you mention above will do as you say, as I said pumps in series cause a number of problems.
I suspect your boiler is supplying its amount of flow rates to maintain its delta t (34KW at DT 20°C = 24.3 LPM) but the UFH is taking most of that and robbing the radiators when both circuits are in demand.

 

[Andycap836]

Is there even a mixing valve on or next to that manifold connected to the pipes? Does the UFH serve all of the ground floor?
A pump as you mention above will do as you say, as I said pumps in series cause a number of problems.
I suspect your boiler is supplying its amount of flow rates to maintain its delta t (34KW at DT 20°C = 24.3 LPM) but the UFH is taking most of that and robbing the radiators when both circuits are in demand.

So, I checked in the utility room - where the boiler & water tank are - and I think the underfloor pump & mixer valve are located there. Pic attached (only reason I think this is, I turned on the underfloor heating and the pump in the pic began to softly vibrate & heated up and the blue topped valve next to it seems to be a mixer valve for UFH (per a google search which lead me to this

22mm - Direct OEM Highflow Heatguard Tempering/Mixing Valve

22mm - Direct OEM Highflow Heatguard Tempering/Mixing Valve - HEAT 219 060, available now from the Advanced Water Company.

www.advancedwater.co.uk

 

[SJB060685]

Yes that is the UFH mixer and pump. Does the UFH do all of the ground floor?

 

[Andycap836]

Yes that is the UFH mixer and pump. Does the UFH do all of the ground floor?

Yes, it does - no rads on the the ground floor. There are 3 thermostats on the walls so the ground floor is split into 3 heating areas even though it's only 50sqm and pretty much all open plan - pointless

 

[SJB060685]

Then as I said before I suspect the UFH is the cause and its pulling the majority of hot water from the boiler when ground floor and first floor are in demand. If we knew or had an idea of the UFH total load I could confirm that with some simple maths.
So where do you go from here? As I said above hydronic separation would be the fix if this is a flow problem, however not too many engineers are familiar with it, or even how it works to be honest and its probably worth seeking the advice of another engineer or firm who do understand it.
Replacing the boiler to fix this is not needed I believe.