Modulating Condensing Bolier - what style pump is recommended ?

[Bert bassett]

Hello,

My second post

Recently I had a Vaillent 418 ecofit pure open vent boiler installed onto an old system ( the installers were rubbish, over promised and under delivered)

I am now looking at getting the best efficiency out of the system and the boiler by getting the return temp below 55 degrees

So i plan to remove the straight through (flow to return) bypass from the last radiator and replace the TRV on that rad with open lockshield valves (is that a good idea ?)

The existing pump is 24 years old, so i am looking at a new pump, i thought it would be straight forwards to get a pump that provided a constant flow (so that the boiler does not cycle as TRV's come in and out).

Maybe i do not understand fully the difference of the Grundfos Alpha 2L (constant pressure and proportional pressure)..... do any of these create a constant flowrate ?

Are they recommended for a modulating condensing boiler ?

Any advice will be appreciated

Many Thanks
Bert

 

[king of pipes]

Dab Evosta gives you the option, any pictures of this install you can go fully trv but you should ensure you have a auto bypass fitted at least 1.5m away from the boiler i cant believe a installer would have left a 24year old pump in on a upgrade ? Good practice is change the pump and valves fit a mag filter , all controls , the programmer , and at least the radiator valves , a chemical clean with a hot flush ,then cold flush . cheers kop

 

[Bert bassett]

Hello Thanks for the reply,

I have looked at so many of those diagrams i am now going mad..... my reason for coming to the forum as i am sure i do not understand them correctly.

The reason i am thinking of removing the bypass across this rad is that this is a curved bay window rad about 2.5m long, i cannot get one side very warm...... all of the heat goes through the bypass.
This rad is the only source of heat in the living room, and i want the most heat out of it.

If i try to balance the other rads to increase the flow through it.... the boiler starts to short cycle.

PS, a new Nest room thermostat controller was installed, along with an ecomag filter.
The filter is on the boiler flow, the wrong place I am sure.... I have contacted the manufacturer for the filter and they have sent diagrams showing it can go anywhere..... so i cannot take that back to the installer.

The system was power mag flushed, but i think all of the pressure went through the bypass...... i have since removed the bay window rad and flushed it with a hose.... the amount of black sludge was unbelievable.

 

[Bert bassett]

a pic of the system

 

[jtsplumbing]

Bit of a mess, is the cover from the diverter valve missing ? you also have a old style bypass just below the pump.

 

[Bert bassett]

big mess.... i was hoping it was all going to be improved.... the cover for the valve is under there somewhere

 

[Harvest Fields]

Did they charge you a fortune?

 

[Bert bassett]

Guess so, not really sure...... the old boiler and heating ran for 24 years without anything ever being done to it....... so trying to be a little bit more modern .......this came with 10 years warranty and service included.... so i figure if the company stays afloat i should have 10 years more of trouble free heating (as if !!!)

 

[Sharp Point]

Is that magnetic filter is on the boiler flow, if so it’s a big no no, as it’s an obstruction to the open vent if the filter valves are closed.

 

[Bert bassett]

Is that magnetic filter is on the boiler flow, if so it’s a big no no, as it’s an obstruction to the open vent if the filter valves are closed.

Yes it is on the flow...... all i could find says it is not to go there.... but the filter manufacturer sent me the pic below

 

[Harvest Fields]

Pic not working

 

[Bert bassett]

from the filter manufacturer

 

[Sharp Point]

What’s the make and model of this filter please?

 

[Harvest Fields]

That diagram does not surprise me. You can fit a magna clean on the flow if there is nowhere else to put it.

 

[jtsplumbing]

Can you do a photo of boiler & pipes, filter is always best on return, idea being its stops rubbish getting back to boiler, but on odd occasions you have to fit it on the flow, maybe position or accessibility of pipe work

 

[Bert bassett]

Yes it is on the flow.... all i could find says it is not to go there.. but the filter manufacturer sent me the pic below

tis now

What’s the make and model of this filter please?

From: TechnicalInta [mailto:[email protected]]
Sent: 28 November 2017 09:01
Technical

Intatec Limited
Tel: 01889 272180
DDI:
Mobile:
Fax: 01889 272191

Sorry i'm at work.... cannot find the link at the mo..... Intatec sent me the info and i think it was for the Eco-Mag

 

[Bert bassett]

tis now


From: TechnicalInta [mailto:[email protected]]
Sent: 28 November 2017 09:01
Technical

Intatec Limited
Tel: 01889 272180
DDI:
Mobile:
Fax: 01889 272191

Sorry i'm at work.. cannot find the link at the mo... Intatec sent me the info and i think it was for the Eco-Mag

Here is the datasheet https://www.mkmbs.co.uk/Root/Documents/L018495.Technical Data.pdf

 

[Sharp Point]

I just find it hard to swallow that they say it’s okay in that position, I had a look on adey’s website who make the magnaleak and they have a cross on their diagram for that filter location.

 

[Bert bassett]

I just find it hard to swallow that they say it’s okay in that position, I had a look on adey’s website who make the magnaleak and they have a cross on their diagram for that filter location.

I also have that diagram.... that is what i wanted Intatec to supply me with, so that i could go back to the installer

 

[Harvest Fields]

My mistake I didn’t look at the picture or post properly. You have an open vented and not a sealed.
Sorry.

 

[Zippymark]

My guess is a new pump will sort of most of your problems. It's probably not pushing at half the force it did when new, this might be why your radiator isn't heating properly and also why the boiler is cycling, to prevent it from overheating due to the low flow of water through it.