How to optimise your combi boiler

dirtychinchilla said:
You can get TRVs that do dynamic balancing. They each have a built in DPCV. Have a look at this. On these Pt40s, you set the design flow rate and it will automatically balance the radiator for you. They virtually eliminate the need for commissioning. As you say, they should be paired with a pump at constant pressure but variable volume. You're unlikely to have these specific valves unless you have a heat network.

I haven't watched his video, but these aren't your typical self balancing TRVs. I also have mixed feelings about him; it's hard to trump 50 years of Danish district heating technology.
Click to expand...

Thanks for mentioning the dynamic balancing valves, I've looked in to them since you mentioned them, not being a plumber I hadn't heard of them before. Do you know if Danfoss to a chrome TRV head for the RAS-B2? It's purely an aesthetic thing so I wouldn't be throwing away perfectly good supplied white TRV heads.
 
A lot of boilers have an internal bypass. My system is on manufacturer controls so it runs the system better by opening the valves before starting the pump and stopping the pump before closing the valves it can do this as it doesn’t use the switch in the valves to activate the pump. It also cycles the valves daily without running the pump to stop them from seizing up.

I’ve been giving my system a check before winter and noticed the external automatic bypass valve is passing water all the time even when fully closed not ideal for keeping the return at lower temps. Will likely remove it as my boiler has an internal one and the hall radiators run with no TRVs.
 
I was going to replace the bypass valve (a manual gate valve set to about 20% open) on my system to an automatic bypass valve, however I'm changing the pumps to Grundfos UPS3 and the installation manual states the proportional pressure mode is not recommended in heating systems with an automatic bypass valve, to ensure a minimum flow for heating appliances.

Proportional pressure mode is the recommended control mode and I wanted to use it to reduce the water hammer effect I get when the hot water motorised valve shuts.
 
Jimbo Mahoney said:
Figured out why my rads were so hard to balance (possibly).

The pump has three settings and it's on the highest.


I'll whack it down to the lowest and re-do the balancing - I suspect our house is small enough that the lowest setting with the lockshields open more would be more suitable.

That would also save a tiny bit on electricity, as it'll be running at 50 watts instead of 70.
Click to expand...

Sorted.

Even on the lowest power, it's plenty for our small house. Just needed to loosen a few of the lockshields which was much easier than setting them up initially.

Updated my post with the, admittedly small, cost saving from the pump using less power.
 
Last edited:
55c seems really low to me, I had mine set at 70c it’s the baxi duo tech boiler which I have , is that a condensing boiler ?
 
Bounce said:
55c seems really low to me, I had mine set at 70c it’s the baxi duo tech boiler which I have , is that a condensing boiler ?
Click to expand...
Yes it's condensing, you can also buy the weather comp kit from Baxi and have the boiler follow a heat curve (adjustable). It's what's fitted to our Baxi duotec (Platinum). Works a treat :)
 
FlyingFish said:
Yes it's condensing, you can also buy the weather comp kit from Baxi and have the boiler follow a heat curve (adjustable). It's what's fitted to our Baxi duotec (Platinum). Works a treat :)
Click to expand...

Thanks , what does it do ? Adjust the temperature of the flow to the radiators depending on the outside weather temperature?
 
Last edited:
Bounce said:
Thanks , what does it do ? Adjust the temperature of the flow to the radiators depending on the outside weather temperature?
Click to expand...
Exactly that, with the kit fitted (small harness conversion and outdoor sensor) the CH temp dial changes it's job to adjust through different types of heat curves, depending on what you would like to have output from the boiler in relation to outside temp.
 
FlyingFish said:
Exactly that, with the kit fitted (small harness conversion and outdoor sensor) the CH temp dial changes it's job to adjust through different types of heat curves, depending on what you would like to have output from the boiler in relation to outside temp.
Click to expand...

Thanks for the info, I’ll see how it goes I suspect in the depths of winter I may need to increase from 55c. At the moment I just have the nest thermostat linked to the boiler , that has worked well since we’ve had it. In all fairness it’s a good boiler , I know baxi don’t have a great rep but it works fine in my opinion.
 
I think you've been misinformed, we (like other companies) have fitted hundreds and hundreds of Baxi duotec (now the 600&800) boilers (excluding the terrible GA model).
They are excellent in design, robust and reliable, and easy for users to operate, also very easy to repair. I'm not going to say they are perfect, but they are pretty dam good at what they are.

They have probably been Baxi's best selling model as I think it's been on the market over 16yrs. It's been tweaked over the years to improve components, but a very solid boiler.
 
Just a quick one so dropped it here hopefully.

On my combi boiler the hot water dial goes 1, 2, 3, 4, 5, e, 6.

What does the e mean? It doesn't say in the manual. It's a Worcester Bosch.
 
Last edited:
Noticed my boiler last couple of days is just starting to come on in the mornings to bring the downstairs up to 18c.
Went to see how the boiler was behaving and it was on at 27c. So Opentherm definitely does it's job.
I don't think the boilers efficiency numbers add up though it was saying 60%
 
FlyingFish said:
E isn't for eco, eco is a separate button and is for the preheat feature.
E on the DHW temperature dial is 50C. It's in the user manual ;)
Click to expand...
I looked through the manual, couldn't see it mentioned. Will check again. Why use an e symbol?


Also I'm considering fitting a Google nest. Currently have what I think is a wireless digistat linked to the Worcester Bosch boiler. Can it be done?
 
Last edited:
My heating has been on since 1st week of sept, i tweaked my combi's CH temp to 70c and the hot water to 55, the CH is just on the mornings, stat is set to 20c.My moms putting on the gas fire on for bit during the day as shes had a cold etc. Had my statement from octopus and surprisingly its only cost me a fiver more than last month. Tweaking the temps definately makes a difference in gas usage. I might try 65c on the CH temp, but on my old draughty house it might take too long to heat up.
 
danlightbulb said:
I looked through the manual, couldn't see it mentioned. Will check again. Why use an e symbol?


Also I'm considering fitting a Google nest. Currently have what I think is a wireless digistat linked to the Worcester Bosch boiler. Can it be done?
Click to expand...

No idea why WB use 'e'
Taken from WB Cdi boiler manual.
0m37Eng.png

The Google Nest thermostat is a good option (I've got one), and if your installer knows what he's doing you can have the Nest control the hot water preheat feature of your boiler, as well as the heating.
 
FlyingFish said:
No idea why WB use 'e'
Taken from WB Cdi boiler manual.
0m37Eng.png

The Google Nest thermostat is a good option (I've got one), and if your installer knows what he's doing you can have the Nest control the hot water preheat feature of your boiler, as well as the heating.
Click to expand...
Thanks.

Was hoping to DIY it. Perhaps need to start my own thread on it with pictures of my current controls as it's wireless.
 
Boilers not cut in yet, thermostat is set at 17 and the temps not dropped below 21 in the house so far, even with the drop in temps overnight.
Looks like the extra layer of insulation in the loft will pay for itself quite quickly.
 
You must log in or register to reply here.
Back
Top Bottom