Vaillant 438 with 3 zones, frequent S53

[matt1e]

Mattle , plenty of 4xx series boilers out there not fitted on a LLH , 30c differential will not flag up an S53.

never said it would, I'm saying it is too high
simply put
If you have a deltaT greater than 20 degrees then it can only mean one thing
the minimum flowrate req is not being met

3.14 Pump specification
The pump should be fitted on the flow pipe from the
boiler
and have isolating valves each side.
A variable duty pump should be set to give a
temperature difference of no greater than 20°C

Matt

 

[matt1e]

Vaillant header is around 200 quid (40kw) , the 'closely spaced tee' arrangement is a yank thing , by the time pipework is altered along with NRV's then the LLH is a better option.

I see far more P/s arrangements using closely spaced tees than using LLH's to be honest
doubt he would need any NRV's
Not that I am saying a LLh isn't a good option btw it just isn't the only or cheapest option
The P/S route is undoubtedly the best route either option

Matt

 

[D_Hailsham]

but this would never allow the boiler to be used at its max capability

I agree. The OP seems fixated on the fact that the house was warm enough in the winter with 26kW.

any links to the data you found on it Dave?

the performance curve would be good to find!
incidentally webcaps recognises the model no when searching for a replacement and suggests an Alpha2 15-50!

That's where I got the head/flow data from!

Unfortunately Grundfos withdraw all info on a product when it removed from the market.

 

[Dan Robinson]

I've said it before. The whole house method is sh|t.

 

[Steelmasons]

You miss the point Mattle , whether all zones are calling (which will be in excess of .46 l/s) or one zone , as long as a MINIMUM (maybe upstairs/downstairs/HW) flow rate is achieved then boiler will not flag up an S53 , of course if all zones are calling the flow rate required for a 38 kw load is 0.46 l/s which the OP obviously has , i'm not disputing that , whether a LLH/bypass/ABV is fitted is besides the point , a flow rate of 0.3 l/s WILL NOT flag up an S53 whether the load is 38kw or 2kw (3 zones or 1 zone) , sorry for the confiusion.

 

[Steelmasons]

Vaillant header is around 200 quid (40kw) , the 'closely spaced tee' arrangement is a yank thing , by the time pipework is altered along with NRV's then the LLH is a better option.

I see far more P/s arrangements using closely spaced tees than using LLH's to be honest
doubt he would need any NRV's


Matt

The closely spaced tee arrangement negates the need for zone valves (tis the nature of hydronics) , but of course each zone WILL require a NRV (normally situated IN suction side of circulator in america) in order to eliminate gravity circulation when zone circulators shut down.

 

[D_Hailsham]

The closely spaced tee arrangement negates the need for zone valves (tis the nature of hydronics) , but of course each zone WILL require a NRV (normally situated IN suction side of circulator in america) in order to eliminate gravity circulation when zone circulators shut down.

You are assuming a pump in each zone and that a pump acts as a valve. This isn't necessarily true, which is why Grundfos incorporate valves in their twin pumps.

 

[Steelmasons]

D hailsham with all due respect you obviously don't know how the 'closely spaced tee' arrangement functions (wasn't it gaswizzard who first bought this to your attention ) , the CST arrangement HAS to have a circulator on each zone , no need for zone valves as long as flow/return for each zone are spaced correctly , what it does require is a NON RETURN VALVE at each zone , otherwise unwanted circulation WILL be an issue through redundant zones.

CST arrangements use eithe single/twin setups , the twin setup (duplicated) will have a flap valve to eliminate unwanted circulation throgh pump body , twin set up DOES NOT use a non return valve , one head is constantly open to flow.

I may have a low post count but bare with me.

 

[matt1e]

Vaillant header is around 200 quid (40kw) , the 'closely spaced tee' arrangement is a yank thing , by the time pipework is altered along with NRV's then the LLH is a better option.

I see far more P/s arrangements using closely spaced tees than using LLH's to be honest
doubt he would need any NRV's


Matt

The closely spaced tee arrangement negates the need for zone valves

but it doesn't mean they cant be used ie
1 primary loop and one pump
1 secondary loop and one pump
secondary loop split into two zones each controlled by a zone valve

Matt

 

[Steelmasons]

Mattle , the whole point of the CST arrangement is to negate the influence of flow through unwanted zones due to the positioning of the 'tees' , what it doesn't do is negate the influence of gravity circulation , the CST arrangement doesn't require zone valves period.

An example being the one pipe heating system , if the flow/return 'tees' were taken off the ring in close proximity to each other the radiator would recieve NO CIRCULATION via circulator BUT , gravity circulation will influence flow.

 

[matt1e]

Since when has a CST arrangement used twin pumps (duplicated)?

CST arrangements use either single/twin setups , the twin setup (duplicated) will have a flap valve to eliminate unwanted circulation throgh pump body , twin set up DOES NOT use a non return valve , one head is constantly open to flow.

you edited that quick

btw the flapper is a non return valve, it prevents recirculation via the other pump

I'm not nit picking like

Matt

 

[Steelmasons]

Since when has a CST arrangement used twin pumps (duplicated)?

CST arrangements use either single/twin setups , the twin setup (duplicated) will have a flap valve to eliminate unwanted circulation throgh pump body , twin set up DOES NOT use a non return valve , one head is constantly open to flow.

you edited that quick

btw the flapper is a non return valve, it prevents recirculation via the other pump

I'm not nit picking like

Matt

Of course the 'flapper' prevents circulation via the redundant head , what it doesn't do is negate gravity circulation , do we really need to explain every detail? , i'm sure you;ve got the jist. , sorry if i've overlooked something

 

[matt1e]

Mattle , the whole point of the CST arrangement is to negate the influence of flow through unwanted zones due to the positioning of the 'tees' , what it doesn't do is negate the influence of gravity circulation , the CST arrangement doesn't require zone valves period.

An example being the one pipe heating system , if the flow/return 'tees' were taken off the ring in close proximity to each other the radiator would recieve NO CIRCULATION.

Steel I am well aware of the influence of gravity circulation mate, and of hydraulic seperation
and I also know that zone valves are not req if the secondary circuit consists of one heating load
I also know that if your secondary circuit is split into more than one load then they are, Period
Has the penny has dropped yet?

Matt

 

[matt1e]

, do we really need to explain every detail? , i'm sure you;ve got the jist. , sorry if i've overlooked something

Oh I think I'll get by

Matt
Ps what you have overlooked is hinted at in my post before this one

 

[Steelmasons]

I also know that if your secondary circuit is split into more than one load then they are, Period
Has the penny has dropped yet?

Matt

Suggest the penny hasn't dropped on your side mattle , the WHOLE point of the CST arrangement is multiple zones off the primary circuit , whther 1 zone or 10 secondary zones off primary circuit it doesn't matter , the spacing of the 'TEES' at each zone will not influence any pumped flow through redundant circuits , this is the whole point of using the CST arrangement , works in exactly the same way as a LLH (as long as LLH does not excees .3 m/s flow rate) , anyway gonna pop over to the CC and make a nuisance of myself.