Improving a microbore system

[D_Hailsham]

I agree with D_Hailsham that the 8mm pipework itself should not block (although it has 90 degree elbows in where it pops out of the wall to feed the downstairs rads) as the flow rate is high (the valves to the lounge rad are fully open). But once the water enters a big rad it will slow down a lot and deposits may well drop (which seems to me to be better than going back to the boiler).

The flow rate through the rad is the same as that through the connected pipes, it's only the velocity which reduces. This will be the same whatever size of pipe is used and will have been taken into account when the rad was designed.

access to the boiler return is very difficult which is why I have proposed putting a filter before the pump

I had the same problem when the boiler was replaced. So I contacted Fernox as the installer suggested putting the filter on the flow before the pump. I got this reply:

The risk is due to the isolation valves, which if shut would create a potentially dangerous situation. The TF-1 will not block with sludge so as to obstruct the flow.

Adrian Dyer
Fernox Technical Services

 

[MrDuck]

Thanks and that's interesting. I presume the concern is that with the isolating valves closed the overflow pipe would be blocked. But I was thinking of a Magnabooster which doesn't have isolating valves like the TF-1. So risk mitigated, I think.

 

[Richardthe3rd]

Thanks and that's interesting. I presume the concern is that with the isolating valves closed the overflow pipe would be blocked. But I was thinking of a Magnabooster which doesn't have isolating valves like the TF-1. So risk mitigated, I think.

I thinks it's more the risk of a 'dead head' circulation pump, which at best will knacker it or a even worse blow up!!

 

[MrDuck]

Not sure I fully see the point. Pumps come with isolating valves anyway, which could be turned off (but only with the use of a tool). I think I will call the Magnabooster people next week and see what they think. The MB3 with external magnet looks interesting, but I hope it doesn't constrict flow, as even with a 6m pump I struggle to get decent flow though my lounge rad.

 

[MrDuck]

D_Hailsham - Well I contacted Spirotech Technical Support (in Holland!) and was advised that if I could not fit the MB3 into the boiler return, then immediately before the circulation pump was a good alternative. So that's what I plan to do!

Thanks again for all the support. I still think there is a greater than usual chance of crud settling in the bottom of my lounge radiator as the achievable flow rate is so low. So I will focus on draining this.

 

[mogget]

Hi,

I've recently installed an MB3 on my own system to protect my new boiler. It was very easy to install, and I like the all brass construction (I am always suspicious of plastic). My Ultracom likes a high flow rate and it doesn't seem to have impacted on that at all, and it's very easy to flush out when required.

Hope that helps.

 

[MrDuck]

Thanks for the feedback mogget. I asked Spirotech if they knew what pressure drop an MB3 would introduce - but they didn't seem to know!! My boiler also needs a high minimum flow (it's a Vaillant) so your experience is all good news.

 

[mogget]

If yours is, as I suspect a Vaillant 400 series it should be fine, the Ultracom is a cut down version of the Vaillant and has broadly similar requirements.

 

[MrDuck]

Yes, I think it's a Vaillant 415 ecotech. Good boiler, but fussy about flow rate.

 

[simond]

If you have flow problems, and an ecoTEC 415 is a blighter for flow resistance, I suggest you fit a low loss header and two pumps.

This will improve system efficiency and give you a higher flow rate round the microbore, and the boiler.

The Worcester header is preinsulated and good value, they say it is to fit two boilers but it works very well with one.

You'll need a relay or two to make it work.