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Hi John, The stove and radiators are on the ground floor and the cylinder, pump and manifold are in the loft section of the top floor. See attached drawing. Coil to Coil vertical height is just under 3m. However, note the cylinder is not an open vented type. It has a pressure release valve...

Unfortunately the designer has decided not to answer any questions after selling their equipment and design and then learning it did not work.... The issue with gravity circulation is that the radiators are located on the ground floor and the manifold in the loft. There are a number of sections...

To be honest I'm a bit concerned with having a close coupled feed which means the cold feed is not directly supplying the return pipe of the stove. In the event of the stove boiling, it seems the cold feed would not easily supply the wet jacket of the stove and it could potentially be damaged...

The Heat Hero Direct seems like an interesting product and related to this discussion: https://heathero.ie/product/heat-hero-direct/ It also comes in a "gravity" model: https://heathero.ie/product/heat-hero-gravity/ The gravity model seems to have several injector tees. I'm not sure if the...

Rayburn recommend the dipped cold feed. See attached.

Hi @Exedon Presumably the alternative to a dipped cold feed is to have it connected directly, vertically, but then the downside is heat can rise up the cold feed pipe and heat the header tank. Do you think the diagram in #42 will work aside from that? I can add in a heat leak radiator.

Hi Jon, In the current original problematic setup (ie where the cavitating pump supplies a manifold which in turn supplies radiators and the DHW tank), the pipe ID size from manifold to radiators and DHW tank is probably around 1/2 inch. If I understand correctly, you suggest having the DHW...

Hi Fixitflav, I meant the static head to the Harworth heating schematic that Jon posted in #31. The F& E tank in my system is above the pump in the loft. I can set it up so it is about 1m above the pump inlet (As per my drawing in #42) The injector tee is a device that has a venturi in it...

Here is an example of the injector tee and pump in the loft and vent and feed going to the pump inlet. The tank thermosiphons and the radiator circuit is pumped. I should be able to get 1m static head between top of water in header tank and pump in this arrangement. Comments?

Thanks for all the help everyone. In my post #24, the schematic is the planned schematic to rectify the current issues. It creates a fully pumped circuit, where a manifold distributes water to the DHW tank and two radiators. The pump switches on via a thermostat positioned close to the boiler...

Thanks John, Do you have any feedback regarding the injector tee and whether there is an alternative to that? Nathan

hi John Will the thermosiphon still work given the return loop is through the pump? Also, if I plumb the tank so it thermosiphons and is a heat sink, then presumably it will not thermosiphon when the pump turns on and directs water through the radiators. It looks like people solve this issue...

See attached schematic I drew up from the various comments. Is this more or less what is being suggested? One question, can this circuit thermosiphon? I currently have the thermostat up near the header tank and pump in the loft, and the water rises up when the fire starts which activates the...

The HW cylinder is fed from the manifold, as are the radiators. The data I found on Wilo NPSH is here, page 7: https://cms.media.wilo.com/cdndoc/wilo252578/3625152/wilo252578.pdf If the check valve is removed and the vent installed up and over, will the issues with low pressure at the pump...

The pump is around 3m above the boiler top. The stove and radiators are on the ground floor and the pump and cistern plus manifold in the loft on the second floor.

I get cavitation with cold water (fire turned off) as well as hot. The pipe ID is 1 inch most of the way with the last ~400mm branch to the pump 20mm. See picture. The suction pathway when the check valve is closed is all the way from header tank, through the wet back stove then back up to the...

The item on the cold return after the manifold is a dosing pot.

The check valve opens into the F&E cistern.

Hi, Yes, solid fuel stove (Rayburn 355sfw). The hot flow pipe goes from the stove up into the cistern via the check valve. The system can thermosiphon with the cistern initially but then when it gets to temperature, the pump turns on and pushes water through the radiator circuit. In theory...

Hi There, I have an issue where a pump is constantly cavitating on a central heating system. Please see screenshot of installed schematic. The system is new and installed as per the schematic supplied by the designer. All lines where bled as well as the pump. The height between the top of the...