Central heating and pumps question!

tred

Folks, here is my setup. I have a boiler in the garage. The boiler is hooked up to a distrubution unit in the utility of the house, and below it are 4 pumps. 1 for water, 1 for upstairs, 1 for downstairs, and 1 for main pump from garage. There is a pipe stat in the garage connected to the main pump. What I am noticing at times, is inconsistencys with the main pump going on and off. for exmaple when the rooms hit the correct temp, the pumps inside for upstairs and downstairs go off, but the main pump doesnt go off, until the pipe stat at boiler goes below 40 degrees say. But now that i think about it, whats the point, its only pumping water from the boiler in garage to the distribution setup, but with the pumps for upstairs and down off, then where else is it going!. I notice it might take ten or 15 mins for the main pump to go off after the zone pumps go off.

Pete67

Hard to be specific without knowing the system design in more detail. Many boilers require that circulation is maintained for a period of time after the burner stops firing to allow a proper cool down. This is particularly true of gas boilers which tend to have a relatively small heat exchanger. Without this cool down the life of the heat exchanger will be geatly reduced.

roy rodgers

sounds like you have a systemlink somethig like this


The pump that is running after when the up stairs down stairs zone has reached temperture is an over run pump. Which from my gathering is circulating through the systemlink to get rid of extra heat from the boiler.
I guess that you might have a oil boiler and the installer put this pipe stat on so the boiler wouldn't over heat.
Personally I wouldn't do this as it would be a waste of energy and oil fired boilers are able to take extra heat in their boilers when they have been shut down.
I find the system lex a great way to wire the heating system up, It brings on the pumps and boiler on when they are needed and doesn't waste on energy.

Outkast_IRE

It is best practice as such to have a overrun on the boiler , as royrodgers mentioned its not as necessary on some oil boilers but i believe i see some manufacturers of the newer higher efficency condesing ones have this feature now.
And do yourself a favour op with that many pumps make sure they are replaced with A rated pumps if they need replacing they actually consume a fair bit of electricity when theres that many.

heinbloed

This type of installation is an experiment which had been hailed in the past. It was always an overkill.
The average household central heating system works with 1 pump,hence the name.
There is usually no technical need to run a pump after the firing has stopped, timed out. Since there is no added heat to the system there is no need to transport it.

These type of installations had been featured by RTE and SEAI, by people who did not understand the basics of a central heating system in times when most households had a gravity based central heating system installed, at times when one had to place a special order in the plumbing shop to get hands on a thermostatic valve.

Get a heating engineer to convince you about the correct aproach.

He/she would very likely recommend the following:
rip out all pumps and replace the main circulation pump with an intelligent A-rated pump.
Get room/radiator thermostats (TRVs)installed, devices which sense the room temperature and open and close the valves of the radiators - according to demand.
An intelligent pump modulates it's hydraulic performance - according to demand.
And check the boiler's efficiency/age, it might be worth it to get a modulating A-rated boiler producing thermal energy - according to demand. This new boiler would include a suitable pump then, as well as a timer.

Insulate the distribution pipes.

The distribution system shown at the picture posted by roy rodgers is a relic of the stone age (in plumbing terms).
It has and had never any technical or economical advantage above most existing methods. A waste of money and resources.

tred

Thanks for the advice folks mixed bags, but i guess i know now why its was done this way. Ill be honest the main pump was wired by the electrician this way, the plumber, didnt realise, but said it was another way, and let it go.

The pumps are all A energy rated. I supplied so was able to define. All insulated. The system link I have is a bit different looking to above. Ill take a photo later. Its performing brilliantly and, i wouldnt change a thing. I was just trying to figure out the use of the pipe stat, now above it makes a bit of sense!.

ChoirGirl

Sorry to come in with a question of my own rather than a reply, but can any of you tell me why a pump is needed for upstairs as I was thinking that if you only want to have radiators upstairs you wouldn't need a pump at all as the hot water will rise naturally. Thanks for any advice.

DoneDL

If you have a system containing a central connection as in the picture the pump is sometimes needed to provide for the upstairs zone. Most properties have only one pump and zoned areas.