plumbing and heating

mjk1988

hello

i was wondering could someone help me with the plumbing term "pipes are crossed" is this a term for when the flow and return have been crossed on connecting up a cylinder/ also i know when piping radiators the the flow pipe and trv are on the right side of the radiator,they can be piped either on right or left am i correct in thinking this,on my heating system when it is turned on at first the flow connections seem to be either on the left or the right when heating up,does this matter????thanks for any info recieved

Dtp1979

mjk1988 wrote: »

hello

i was wondering could someone help me with the plumbing term "pipes are crossed" is this a term for when the flow and return have been crossed on connecting up a cylinder/ also i know when piping radiators the the flow pipe and trv are on the right side of the radiator,they can be piped either on right or left am i correct in thinking this,on my heating system when it is turned on at first the flow connections seem to be either on the left or the right when heating up,does this matter????thanks for any info recieved

Flow can be on either side. It doesn't matter at all. As for the term pipes crossed, I think you have your wires crossed

mjk1988

I thought if you mixed up the flow and return to the cylinder,as in the flow at the bottom connection and return at the top this is the term pipes crossed,bottom connection heating up first instead of top

corkgsxr

mjk1988 wrote: »

I thought if you mixed up the flow and return to the cylinder,as in the flow at the bottom connection and return at the top this is the term pipes crossed,bottom connection heating up first instead of top

That just stops proper stratification.

I'd think it only refers to hot and cold pipes

mjk1988

Cheers thanks for your help

DublinDilbert

Water will want to naturally flow a particular direction depending on if its temperature is being increased or decreased. You can try force it to flow the opposite direction with a pump but its best to have the pump and the natural flow going in the same direction.

The exact same thing happens in a car cooling system:- As the water heats up in the engine it expands, making it less dense (lighter) so the hot water comes off the top of the engine block. The top of the engine block is plumbed to the top of the radiator (top hose is always the hottest). The radiator takes in hot water at the top and cools it down, as it cools down it becomes more dense (heavy) and falls, returning to the engine via the lower hose.

A hot water cylinder is exactly like a car radiator, so the warmest water (coming from the boiler) should go to the top heat exchanger coil connection and the return to the boiler of the cooler water should come from the bottom, exact same as a car radiator.

Best not try fight physics with a pump

mjk1988

very well explained thanks :-) much appreciated

corkgsxr

DublinDilbert wrote: »

Water will want to naturally flow a particular direction depending on if its temperature is being increased or decreased. You can try force it to flow the opposite direction with a pump but its best to have the pump and the natural flow going in the same direction.

The exact same thing happens in a car cooling system:- As the water heats up in the engine it expands, making it less dense (lighter) so the hot water comes off the top of the engine block. The top of the engine block is plumbed to the top of the radiator (top hose is always the hottest). The radiator takes in hot water at the top and cools it down, as it cools down it becomes more dense (heavy) and falls, returning to the engine via the lower hose.

A hot water cylinder is exactly like a car radiator, so the warmest water (coming from the boiler) should go to the top heat exchanger coil connection and the return to the boiler of the cooler water should come from the bottom, exact same as a car radiator.

Best not try fight physics with a pump

Out of most boilers first thing your doing is pumping it down. Heating pumps are quite powerful.

Reason you go hot in top it's so your not disturbing stratification of the cylinder.
Other way round your putting the hot into the coldest part. So it takes longer for you to get hot water.

DublinDilbert

corkgsxr wrote: »

Reason you go hot in top it's so your not disturbing stratification of the cylinder.
Other way round your putting the hot into the coldest part. So it takes longer for you to get hot water.

Lots of respect for the regular posters here which I've learnt lots from over the years. I don't fully understand the above, cause the top of the cylinder will be the warmest part of the cylinder, the hot water will collect at the top (due to it being less dense).

So if your putting hot water into the top of the heat exchanger your putting it into the hottest part of the cylinder, not the coldest part

corkgsxr

DublinDilbert wrote: »

Lots of respect for the regular posters here which I've learnt lots from over the years. I don't fully understand the above, cause the top of the cylinder will be the warmest part of the cylinder, the hot water will collect at the top (due to it being less dense).

So if your putting hot water into the top of the heat exchanger your putting it into the hottest part of the cylinder, not the coldest part

If you do it right hot goes in the top. Hot is going into the hottest part of the cylinder. Then proper heat stratification occurs.

Do it wrong and you putting the hot into the coldest part. You end up with colder water going through the hottest part of the cylinder. Meaning the cylinder won't heat right. The whole cylinder heats as one rather than from the top down. It's much slower.

It has nothing to do with ease of pumping. It's because that's the way the cylinder needs it that way to heat faster.

DublinDilbert

corkgsxr wrote: »

If you do it right hot goes in the top. Hot is going into the hottest part of the cylinder. Then proper heat stratification occurs.

Do it wrong and you putting the hot into the coldest part. You end up with colder water going through the hottest part of the cylinder. Meaning the cylinder won't heat right. The whole cylinder heats as one rather than from the top down. It's much slower.

It has nothing to do with ease of pumping. It's because that's the way the cylinder needs it that way to heat faster.

Ahh right I see what your saying. if its backwards it will be a battle to raise the temp in the whole cylinder, rather than from the top down as normal.

corkgsxr

DublinDilbert wrote: »

Ahh right I see what your saying. if its backwards it will be a battle to raise the temp in the whole cylinder, rather than from the top down as normal.

Yes. It's nothing to do with whatever way is Easy to pump.

Unless a system has been designed to work as a gravity system then if the pump fails the system will do bigger all.

And if youv ever drove a car with a shagged pump the way it's pipes doesn't help. There's too much restriction for a gravity circuit to form

mjk1988

thanks very much for all the info much appreciated