Flow- Vent- Feed -Pump

[desktop987456]

If you mean a PRV as in pressure relief valve then there must be a pressure gauge somewhere as well, either on the boiler or after the filling valve
I have a pressure relief valve on my boiler but no EV, as mine is a OV system.

Yes, it has a pressure relief valve but no guage. I know its a funny system that I am trying to understand as well!

 

[desktop987456]

When you source an EV for the system, if sealed is the way you're going, then just get a sealed system kit. It'll come with the EV, 3 bar PRV, gauge, filling loop and a 4 way coupler to connect it all up. You just need to size the vessel accordingly.

View attachment 313449

Many Thanks again, just the info I was looking for.

 

[desktop987456]

Update : I thought I'll update people who helped me with the install process.
To summarise 7 pages;
the location where I wanted to install the boiler had a height constraint of 7 ft as I wanted to install Viessmann heat only boiler as OV.
The min head required was 0.1m from water level in cistern to boiler (confirmed by UK viessmann).
Viessmann also confirmed that it is an OV boiler but can be used for sealed system as well.
I inherited the system and it did not follow any standard; the system was a hybrid (sealed and OV) since it had a cistern (at atmospheric pressure) with a non return valve inside and a PRV at boiler as well. It also did not have any vent pipe.

As I wanted to install an easy to maintain and simple system, I went with a OV system (instead of sealed system) as the title of the post suggests.

-: Removed NRV from cistern
-: maintained max distance of 150mm based on VCP principle
-: installed feed cistern at 0.1m head (including water level at cistern) using 15mm pipe for feed.
-: Kept OV pipe 1 ft higher than the water level at cistern to avoid pumping over.
-: installed magnetic filter on return line.
-: pump was installed on the flow side.
-: made a wooden box to insulate the boiler as it is a room sealed boiler but I have installed it externally.
-: ran a switch wire from inside building to boiler location for thermostat

Briefly tested the system for leaks (boiler in service mode) and fixed them with no pumping over issue yet; after some purging, Rads closer to boiler (2) were very hot but others were luke warm. I still need to balance the system. I do not have any TRVs on Rads. Its just a matter of choking back flow and fully opening return so last rad on system gets flow.

I am not confident about pump settings yet. I saw a couple of posts this morning on pump settings and was wondering should it be set to constant or proportaional setting?

I have only tested it on constant setting. Any advice on pump settings?

 

[fixitflav]

Good to hear it's working OK, just needs a bit more balancing.

I am not confident about pump settings yet. I saw a couple of posts this morning on pump settings and was wondering should it be set to constant or proportaional setting?

I have only tested it on constant setting. Any advice on pump settings?

johntheo5 has put a lot of thought into this! He can probably comment, with charts . I have a basic system and it seems happiest with the pump at constant, minimum speed.

 

[Johntheo5]

You have a Wilo pump?, what is its exact model and modes of operation, what CP setting is it on now?
I have a Wilo Yonos Pico set to a PP setting of 4.6M, this results in the required head of 3.3M for my 10 rad, 8 TRVd rads. Pump power varies between ~ 22/24W and 14/16w with TRVs throttling down. You don't have TRVs so a CP Setting may be more appropriate but constant speed CC is more appropriate if you have a automatic bypass valve ABV, installed.
You said, I think, earlier on, that your previous system had no open vent but also had a NRV on the cold feed, I have seen plenty of these systems around me where the system was converted to what is often described as a semi sealed system but obviously have a EV as well with a pre pressure of 0.5bar, more forgiving than the normal sealed system.

 

[desktop987456]

Flomasta make with 6m head. No ABV installed.
CH Current load - 10-12kw with 10 rads. As per my Heat loss calculations, I have oversized radiators by ~30-35%.
Essential load (2 double panel rads, 48 and 40 inches; 2 single panel rads 55 inches each; 1 fan coil unit ~2.5kw + 3 small bathroom rads), other rads in guest rooms will be used once in a while.

I intend to run at flow temp of 55degC; 55+45/2 minus design temp of 15degC i.e. 35degC

You don't have TRVs

I don't have TRVs but I will not be running all rads so I thought a delta P pump would adjust the varying flow rate?

no open vent but also had a NRV on the cold feed

Yes, which I have removed now that I am following UK standard.

I forgot to add that I have 22mm primary pipework around boiler loop and 19mm secondary pipe work which narrow down to 15mm just before the rads.
Thanks in advance.

 

[Johntheo5]

That pump does not have constant pressure mode, it has the traditional CC or fixed speed settings of 2M,3.8M & 6M, it also has numerous PP settings of 1,2,3,4&5M. What mode and setting are you on?

 

[desktop987456]

I don't understand its settings clearly and I have tested it on c3 (max speed) but thought I ask before switching it to other settings.
Based on my load which setting should I run it on. My back of the envelope working indicates a flow of 600 litres/hour based on a load of 9kw? Based on this which setting should I run this pump on? Thanks

 

[Johntheo5]

600LPH or 0.6m3/hr is a pretty good estimation IMO, C3 will give a head of 5.7M at that flowrate, if your rads aren't all getting hot at that setting then you have a problem somewhere else, C2 would normally satisfy that requirement.

 

[desktop987456]

600LPH or 0.6m3/hr is a pretty good estimation IMO, C3 will give a head of 5.7M at that flowrate, if your rads aren't all getting hot at that setting then you have a problem somewhere else, C2 would normally satisfy that requirement.

What about other PP settings? I haven't tested it yet.

 

[desktop987456]

if your rads aren't all getting hot at that setting then you have a problem somewhere else, C2 would normally satisfy that requirement

Thanks, probably I have only balanced the first two rads which are closer to the boiler and not others. I need to balance the rads first and then set the pump speed? I thought setting the pump speed first and then balance the rest of the radiators.

 

[Johntheo5]

I would balance them on C2.
For sure do not attempt balancing on any PP setting.

 

[MagicDoughnut]

Open vented works off head of tank pressure while sealed works off mains pressure. Plus with a sealed system you get your loft space back.

 

[Madrab]

Certainly sounds like you're on your way. I think you would need to go with a medium setting, C2 is certainly the place to start as suggested, and then perform a balancing exercise throughout the whole system. You need to settle and tune the system so it heats up uniformly, then if alterations to pump settings are required for heat up then that becomes part of the fine tuning process. Open up all valves on the rads and mark which ones are the flow then start the balancing.

Your system is somewhat convoluted, given your site conditions so balancing will be important to ensure all the rads get what they need at the same time.

Without looking back are all the feeds to the rads in 1/2" from a 3/4" backbone, given it's the US or are they metric 22mm>15mm?

 

[desktop987456]

I would balance them on C2.

C2 is certainly the place to start as suggested

C2 was indeed the setting that balanced all rads. I had already marked the flow on rads so balancing was smooth and all rads heated up nicely; the farthest one on the circuit took its time but it got to the temperature at the end.

feeds to the rads in 1/2" from a 3/4"

Correct.

Your system is somewhat convoluted

Why would you say that now that I have followed BS for OV!

The last quirk is setting up of Room Stat/control as the boiler is running in 'Serv' mode?
It gets on/off from Room Stat but boiler is running only when I reset it and it starts in 'Serv' mode only.

Any idea how do I get it into normal mode and set the flow temp?
Thanks