New rads help?

[Matthew]

Hi,

We have recently moved to a larger house with what has turned out to be an unusual heating system. We have just had all the rads replaced with Stellrads and a new Grundfoss SS pump fitted. It turns out that downstairs is a single pipe system in the solid floor but upstairs is modern two. The upstairs rads are fine but downstairs still are not very efficient. I have tried balancing the system by stopping down all the upstairs rads so that they are only open half a turn and this has helped downstairs. I dont really want to get involved with putting a dual pipe system in downstairs however I do have an idea to improve things further, what if I insert a stop down valve in the main pipe feed to the upstairs system therefore forcing more water downstairs? Practical? Difficult? BTW Is it common practice to run a Grundfoss SS on the highest speed setting 3?

Thanks for any advice, Matthew

[Christian McArdle]

Good luck. It helps if the upstairs rads have working and well adjusted TRVs. When these close down, more water is forced through the single pipe system.

However, you may never be able to get the system working particularly satisfactorily with the current pipework layout. The overall upstairs balance may help. If the pipework is already in a suitable configuration for such a valve, you may find subzoning upstairs and downstairs helps, particularly if it is possible to have a pump for each zone.

Christian.

[Andrew Gabriel]

That's not necessary. Single pipe systems worked fine. It's just that there aren't so many plumbers around nowadays who understood exactly how they worked, and the thermal calculations are more complex and well beyond most plumbers today.

Are you sure there isn't one already? In the days of single pipe systems, the balancing was normally done per circuit rather than per radiator anyway, and a mixture of single pipe and dual pipe circuits was not uncommon in the same system.

[bigcat]

If you can pump signficantly faster than usual thru the single pipe section, it should work fine.

If your existing pump cant get the last rad on the single line hot, maybe a 2nd pump in the single pipe circuit only.

It isnt ideal, but it can work well enough.

NT