Grundfos Alpha 3 Pump Settings for Hydronic Balancing

[hallra]

Hi Forum,

I am attempting to manually balance the radiators in my house, to get an average of 11c drop between Flow and Return on each radiator.

I have set the boiler temprature to 65c.

With the Grundfos Alpha 3, it has several control modes, with each mode needing a value set:

Constant Pressure requires a setpoint in metres.
Proportional Pressure requires a setpoint in metres.
Constant Curve requires a setpoint percentage.
Radiator Mode (Auto Adapt)

- Most manual balancing advice out there, states to start with a run speed of II, then change it if the 11c balancing can't be achieved.

With this option not avaiable, would running a constant curve (which I believe is a constant speed) at say 65%, be the way to go or I should be using something else?


All advice would be much appreciated


Thanks

 

[John.g]

Before I do so, is that a safe thing to do in terms of protecting the system & boiler, is running that high ok?
- I presume it is as you are a cautious Guy...

I’m guessing it is fine as it would only be a max 2.3/2.4 at boiler, plus the PRV opens at 3 bar for ultimate protection.
Only question would be is would it be making the boiler work too hard.

Sorry for all the questions.

No it won't make the boiler work any harder, the main reason for limiting it to 2.25/2.35 bar (E.vessel 2.0/2.1 bar) is to ensure that the safety valve doesn't start "feathering" a little early at say 2.7 bar and continue to leak as they sometimes do especially if a lot of crap has/is circulating around.

Why don't you bring the boiler up to temperature as is and per suggestions above and post the final pressure before going any further? You probably have a fair idea anyway what it is.

 

[hallra]

Yep boiler is off and system is cooling down

I’m gonna pm you, probably everyone on the forum is fed up of our public posts by now

 

[John.g]

Yep boiler is off and system is cooling down

I’m gonna pm you, probably everyone on the forum is fed up of our public posts by now

Ok, grand.

 

[hallra]

Doh, there is a setting on your profile blocking PMs, perhaps you are fed up with me

The setting to change is under profile -> privacy

 

[John.g]

Doh, there is a setting on your profile blocking PMs, perhaps you are fed up with me

The setting to change is under profile -> privacy

Doh, there is a setting on your profile blocking PMs, perhaps you are fed up with me

The setting to change is under profile -> privacy

Can someone guide me through this please re changes to make to allow sending private messages or whatever.

 

[hallra]

Can someone guide me through this please re changes to make to allow sending private messages or whatever.

This is how I access it via the mobile app, that icon, 3rd from the left, opens up my profile and then I go to the privacy menu. Scrolling down I get to a setting that lists who can can’t contact me...

Another way to do it, would be to go under my name and press the follow button, you then should be able to send me a PM, to do that press the email icon and type in my username ‘hallra’

 

[hallra]

try emailing me on [email protected]

I'll give you my real email once there.

 

[John.g]

Doh, there is a setting on your profile blocking PMs, perhaps you are fed up with me

The setting to change is under profile -> privacy

What exact settings do I change in Privacy??

 

[hallra]

What exact settings do I change in Privacy??

This bit, start conversations with you... change to members only.

or just use the email

 

[hallra]

I got your conversation and replied to it

 

[doitmyself]

View attachment 36981

This just doesn't make sense.

The OP says he has an Ultracom 24 hxi boiler, which has a 24kW output; but the App says the energy consumption is 29kWh. Is that the current rate or the total since the pump was first installed?

FYI, here are some numbers I took yesterday when trying to manually balance with the pump on:
- I think the system had been heating around 10/15 mins, I didn't note it down, I can't remember which pump setting I had it on, possibly CC at 65%, I would need to repeat to be 100%.

View attachment 37039

1. Why are you using a flow temp of 65C? It will reduce the rad output considerably.
2. How, and where, are you measuring the temperatures? The drop of about 20C from boiler to rad seems excessive.
3. The Ultracom is designed for a 20C differential. An 11C differential will result in a pressure loss through the heat exchanger of nearly 6 metres, compared to 1.8m with a 20C differential. This is at max output.

You say, in another post, that the boiler continually short cycles. This is probably due to the boiler being oversized. (24kW for approx 12kW of rads.) The boiler's logic says that, every time it restarts it does so from max output and then modulates down if necessary. Unfortunately it doesn't modulate fast enough so the temperature rises very quickly, the boiler overheats, shuts off, and the whole cycle starts again.

The reason for over-sizing the boiler is: Hot Water. The system "designer" assumes that the HW cylinder is being heated at the same time as the CH is running flat out. The solution is simple - heat the cylinder when CH requirement is minimal or non-existent. (Modern HW cylinders retain their heat for a very long time.) Installations with Weather Compensation have to be configured so that HW takes priority over CH. If it didn't, the flow temperature might not be hot enough to heat the cylinder. Although you don't have weather comp, you could sill adopt the same principle and give HW priority over CH.

It might be possible to reduce the max output of the boiler using parameter d.0 (See the installation manual).

 

[hallra]

This just doesn't make sense.

The OP says he has an Ultracom 24 hxi boiler, which has a 24kW output; but the App says the energy consumption is 29kWh. Is that the current rate or the total since the pump was first installed?



1. Why are you using a flow temp of 65C? It will reduce the rad output considerably.
2. How, and where, are you measuring the temperatures? The drop of about 20C from boiler to rad seems excessive.
3. The Ultracom is designed for a 20C differential. An 11C differential will result in a pressure loss through the heat exchanger of nearly 6 metres, compared to 1.8m with a 20C differential. This is at max output.

You say, in another post, that the boiler continually short cycles. This is probably due to the boiler being oversized. (24kW for approx 12kW of rads.) The boiler's logic says that, every time it restarts it does so from max output and then modulates down if necessary. Unfortunately it doesn't modulate fast enough so the temperature rises very quickly, the boiler overheats, shuts off, and the whole cycle starts again.

The reason for over-sizing the boiler is: Hot Water. The system "designer" assumes that the HW cylinder is being heated at the same time as the CH is running flat out. The solution is simple - heat the cylinder when CH requirement is minimal or non-existent. (Modern HW cylinders retain their heat for a very long time.) Installations with Weather Compensation have to be configured so that HW takes priority over CH. If it didn't, the flow temperature might not be hot enough to heat the cylinder. Although you don't have weather comp, you could sill adopt the same principle and give HW priority over CH.

It might be possible to reduce the max output of the boiler using parameter d.0 (See the installation manual).

Hi Doitmyself (Great username!)

Welcome to the conversation.

Let me by first stating I'm a moderately knowledgeable DIYer, so apologies if I do something incorrect or ask questions that may look to a expert silly.

I will try to answer your questions as best as I can, however, be aware, that I am still gathering information, testing things out, so it is a work in progress, a lot of work/progress has been made behind the scenes. - A BIG thanks to John.G!
- Thus, it is probably wise to park questions for now as many things are changing on a rapid basis and thus I won't be able to keep you up to speed with everything.
- Once the situation has settled and good progress made, I will post an updated status.


Background
----------

The Heating System was designed and installed by the builder 'Persimmons', it has never worked well since day one, they have constantly avoided fixing issues, I've had to make a number of changes due to component failures and/or incorrectly installed components. (Valves the wrong way around, non-commissioned boiler, failed pumps, failed expansion thank, leaks, etc, etc)

- I've had to live in the cold for some time, as in cold spells the system hasn't heated the house well. Which doesn't help me at all, as I have a severe longterm illness/disability, the cold cripples me.


Replying to your comments
-------------------------


The energy consumption is from a status page of the mobile app that talks to the pump via bluetooth, it is not connected to what the boiler is consuming.

1) The boiler is set to 65c as was advised by Glowworm, we are looking at adjusting this.

2) For the temperature readings you refer to, I had a InfraRed Gun pointed at the steel panel of the radiator, about an inch in from the flow and return valves. (Valves are at the bottom of each rad)
- These numbers were taken with the pump settings too low and lockshields closed a fair bit.
- Through testing, pump settings and throttling has changed a fair bit and far better results are being seen, will publish numbers again when testing/adjustments have been finalised.

3) Yep, understand what you say, a 20C differential is something being looked at, tested.

4) H/W priority is an interesting one and something being looked at.
- I will read up about parameter d.0


Thanks again for coming into the conversation.

Richard

 

[doitmyself]

The Heating System was designed and installed by the builder 'Persimmons'

I'm sure you appreciate that Persimmon would have sub-contracted the design and installation to a third-party, selected on the basis of who was the cheapest. You may be able to find, from the documentation provided with the house, who the actual installer was.

The energy consumption is from a status page of the mobile app that talks to the pump via bluetooth, it is not connected to what the boiler is consuming.

OK. I'll have to investigate this further

The boiler is set to 65c as was advised by Glowworm, we are looking at adjusting this.

Where did you get this info from? I hope the system designer took this into account!

I had a InfraRed Gun pointed at the steel panel of the radiator, about an inch in from the flow and return valves.

IR thermometers can give false readings as they depend on the emissivity of the material (shininess) they are pointed at. So a bright copper pipe will give a lower temperature reading than one which is oxidised. If the rad/pipe is painted the reading will be fairly accurate. It might be helpful to measure the temperature of the flow and return pipes where they enter the boiler . wrap some black insulation tape round the pipes if they are unpainted copper and point the IR gun at the tape.

Yep, understand what you say, a 20C differential is something being looked at, tested.

You may be able to achieve a higher differential by reducing the pump speed and opening the LS valves a little. It's trial and error.