Is this pump fitted the wrong way around?

henke · 08-04-2021 10:10am #1

Hi,

Have back boiler plumbed from my fireplace but I am not noticing when it is not even lit that the pump for it in the hot press can kick in with just the oil boiler on. I had a plumber look at it and he says in his opinion the pump is fitted looks the wrong way around. Does he sound right? Any thoughts on why it could have been fitted like this in the first place? Just want to be sure before I get it changed if necessary.

Pic is the pump on with green light - only oil central heating on.

John.G · 08-04-2021 12:00pm

Which way is the arrow pointing on the pump body, left to right or right to left?

Where does this pipe connect into the back boiler, is into the bottom (return) of the boiler or the top, boiler flow?

Any idea of the other pipe connections?

A pipe stat is probably bringing in this pump can you find its location and setting?.

henke · 08-04-2021 12:17pm

John.G wrote: »

Which way is the arrow pointing on the pump body, left to right or right to left?

Where does this pipe connect into the back boiler, is into the bottom (return) of the boiler or the top, boiler flow?

Any idea of the other pipe connections?

A pipe stat is probably bringing in this pump can you find its location and setting?.

Assuming this what you mean, the arrow it goes right to left?

I'm not sure, there is two pipes on the bottom left of the first pic that go to down the the stove.

The stat is set to 55. It was lower but plumber adjusted it up slightly to see if it makes any difference. He didn't think this was the problem though and the pump still kicks in. Also, the lefthand side of the stove is warm too when the central heating is on so hot water is obviously circulating down there (stove not lit). I don't know if that should be the case. I would be right to say the back boiler pump should never need to kick in when the central heating is on?

John.G · 08-04-2021 12:40pm

Yes, if the arrow on the Halm pump body is pointing from left to right then the flow must be into the boiler return because the non return valve to the right of the pump allows flow from left to right but not in reverse.
Its not clear to me but the picture of the stat looks as if its on the return from the cylinder coil, can you confirm this or otherwise?.
Without seeing the whole piping arrangement it is difficult to see where the OF boiler is re circulating the hot water, ONLY with back boiler off turn up the stat to max (fully clockwise) this should stop the pump and see if the pipework in/out of it stay very hot, make sure you return the stat to its original setting before lighting your fire.

henke · 08-04-2021 1:07pm

John.G wrote: »

Yes, if the arrow on the Halm pump body is pointing from left to right then the flow must be into the boiler return because the non return valve to the right of the pump allows flow from left to right but not in reverse.
Its not clear to me but the picture of the stat looks as if its on the return from the cylinder coil, can you confirm this or otherwise?.
Without seeing the whole piping arrangement it is difficult to see where the OF boiler is re circulating the hot water, ONLY with back boiler off turn up the stat to max (fully clockwise) this should stop the pump and see if the pipework in/out of it stay very hot, make sure you return the stat to its original setting before lighting your fire.

I think the stat is on the return from the cylinder which the plumber said he wouldn't expect. Would that be right?

So turn the stat to max and put on the oil and check the pipes coming in out of the pump?

John.G · 08-04-2021 1:23pm

I wouldn't expect the stat in that position either, to prove that this is the stat, if the back boiler pump is off turn the stat down to minimum, pump should start, if pump running, turn stat up, pump should stop, then leave in this position temporarily to check reverse circulation with OF boiler on.

If back boiler is on..on its own, do you get reverse circulation through the OF boiler?.

henke · 08-04-2021 2:22pm

John.G wrote: »

I wouldn't expect the stat in that position either, to prove that this is the stat, if the back boiler pump is off turn the stat down to minimum, pump should start, if pump running, turn stat up, pump should stop, then leave in this position temporarily to check reverse circulation with OF boiler on.

If back boiler is on..on its own, do you get reverse circulation through the OF boiler?.

Turned the stat to minimum and the pump kicked in. No heating of any kind on. Probably due to warm water in the system?

Turned the stat to max and put on the Oil and the two pipes on the right I think are coming from the boiler as they are piping hot. Those and the red line to the right of the pump are scorching where you can't hold the pipe in your hand. To the left on the Amber line it is more lukewarm and can hold it easily and it gets colder as you move along but I think this warming the longer I leave the heat on.

I can light the fire later or tomorrow when all pipes are cold and check what gets warm with the stat at its original setting.

Lewis_Benson · 08-04-2021 2:51pm

I have the exact same issue.
My oil fired boiler and the stove are not fully isolated from each other, so the stove and its side of the circuit get warm when the oilf fired boiler is firing.
Hige waste of oil, as its effectively heating the equivalent of another 5 or 6 rads.
Ill be getting it sorted soon.

henke · 08-04-2021 3:41pm

Yeah I am just trying to get more confirmation that the plumber is right and the pump is the wrong way round and if so, why did the original plumber fit it like so. I don't know much about plumbing but my understanding is the oil fired burner should never activate the pump, only the stove should and they should be isolated and the oil heating should not send hot water to the stove. Interesting you say it is a huge waste of oil too.

Lewis_Benson · 08-04-2021 4:04pm

henke wrote: »

Yeah I am just trying to get more confirmation that the plumber is right and the pump is the wrong way round and if so, why did the original plumber fit it like so. I don't know much about plumbing but my understanding is the oil fired burner should never activate the pump, only the stove should and they should be isolated and the oil heating should not send hot water to the stove. Interesting you say it is a huge waste of oil too.

All depends how its plumbed.
May have been left this way for safety sake.
If the water was blocked from entering the stove circuit, then there may be no open vent for the oil side, which could be dangerous if the oil side ver overheated and had nowhere to go.

Is there any sort of link manifold device any where?(I doubt there is)

henke · 08-04-2021 4:12pm

Lewis_Benson wrote: »

All depends how its plumbed.
May have been left this way for safety sake.
If the water was blocked from entering the stove circuit, then there may be no open vent for the oil side, which could be dangerous if the oil side ver overheated and had nowhere to go.

Is there any sort of link manifold device any where?(I doubt there is)

Not that I am aware. This is confusing me now on if I should/should not get it adjusted. Wasting oil and triggering the stove pump I guess is not ideal as it is.

John.G · 08-04-2021 4:51pm

henke wrote: »

Turned the stat to minimum and the pump kicked in. No heating of any kind on. Probably due to warm water in the system?

Turned the stat to max and put on the Oil and the two pipes on the right I think are coming from the boiler as they are piping hot. Those and the red line to the right of the pump are scorching where you can't hold the pipe in your hand. To the left on the Amber line it is more lukewarm and can hold it easily and it gets colder as you move along but I think this warming the longer I leave the heat on.

I can light the fire later or tomorrow when all pipes are cold and check what gets warm with the stat at its original setting.

The non return valve should stop any flow of water if coming from the OF boiler, you say its red hot going from right to left, if so this might indicate a faulty NR valve or some one may have removed the flap from it (unlikely), it can be checked by isolating the system and removing the top of the NR valve, its also important that the NR valve is inclined just very slightly "leaning backwards" from right to left to ensure that the flap closes under gravity, it should certainly at the very worst be level, I would check this out first and remove the top of the NR valve, the flap can the be removed, there may just be a bit of sludge holding it open.
There should also be another NR valve somewhere close to the OF boiler to stop reverse circulation through this to stop the back boiler pumping water around the this system.

henke · 08-04-2021 5:11pm

John.G wrote: »

The non return valve should stop any flow of water if coming from the OF boiler, you say its red hot going from right to left, if so this might indicate a faulty NR valve or some one may have removed the flap from it (unlikely), it can be checked by isolating the system and removing the top of the NR valve, its also important that the NR valve is inclined just very slightly "leaning backwards" from right to left to ensure that the flap closes under gravity, it should certainly at the very worst be level, I would check this out first and remove the top of the NR valve, the flap can the be removed, there may just be a bit of sludge holding it open.
There should also be another NR valve somewhere close to the OF boiler to stop reverse circulation through this to stop the back boiler pumping water around the this system.

So just so I understand the pipes coming from the Oil Boiler should be hot since the boiler is on but once it gets to the NR valve it should be cold to the left side of that ie no hot water heading left past the NR valve point towards the pump?

Looking at it there may be slight lean from right to left. Hard to tell but its fairly minimal, certainly level or below left of the NR valve.

Any thoughts on what the plumber said regards the pump being fitted the wrong way around?

wiz569 · 08-04-2021 5:58pm

Just to be clear the arrow @John.G mention above is not the one in your picture but the one on the actual side body of the pump.

henke · 08-04-2021 6:25pm

wiz569 wrote: »

Just to be clear the arrow @John.G mention above is not the one in your picture but the one on the actual side body of the pump.

Thanks for that. Didn't notice the arrow on top on the pump body. It is going from left to right if that helps anyone clarify anything.

John.G · 08-04-2021 6:59pm

If the plumber thinks the pump is the wrong way round then the NR valve would have to be as well as they both must point in the same direction, be it right or left.
If you can establish where the pipe to the right of the NR valve goes to, then that will solve the question.

Re (again) the pipe stat positioning, some pipe stats are located on and very close to the (back) boiler flow pipe, others suggest having it on the return to the boiler to prevent the return water being too cool and causing corrosion but having it on the cylinder return is IMO unusual as its not measuring the actual temperature from the rads & the HW cylinder coil.

henke · 08-04-2021 7:47pm

John.G wrote: »

If the plumber thinks the pump is the wrong way round then the NR valve would have to be as well as they both must point in the same direction, be it right or left.
If you can establish where the pipe to the right of the NR valve goes to, then that will solve the question.

Re (again) the pipe stat positioning, some pipe stats are located on and very close to the (back) boiler flow pipe, others suggest having it on the return to the boiler to prevent the return water being too cool and causing corrosion but having it on the cylinder return is IMO unusual as its not measuring the actual temperature from the rads & the HW cylinder coil.

Yeah just noticed there is an arrow on the NR valve going from left to right also so I am not sure what exactly he meant when he said the pump is the fitted the wrong way. I believe the pipe to the right is going down to the oil burner and up and into the Cylinder. See pic. Pipe to the left of the pump going to the Stove.

I have attached maybe a clearer pic of the stat. It is to the left of the Cylinder as you look into the hot press.

John.G · 08-04-2021 8:06pm

Can you see where the pipe on the left of the pump connects to the stove, ie to the flow (upper) or the return (lower) connections?.

henke · 08-04-2021 8:33pm

John.G wrote: »

Can you see where the pipe on the left of the pump connects to the stove, ie to the flow (upper) or the return (lower) connections?.

I can't see as its an inset stove but I lit it a while ago and this what I observe

Immediately left of the pump is only slightly warm (pump not kicking in yet) and as you travel along that pipe (away from pump) in the direction of going to the stove it gets warmer (not roasting) marked WARM.

Behind that is a second pipe from the Stove which is much hotter and goes straight up and then splits into the cylinder and also up into the attic. If any of this explains which is which.

To add, the pipes downstairs closer to the OF boiler are stone cold so don't think there is the issue with hot water generated from the stove going that way.

John.G · 08-04-2021 9:42pm

henke wrote: »

I can't see as its an inset stove but I lit it a while ago and this what I observe

Immediately left of the pump is only slightly warm (pump not kicking in yet) and as you travel along that pipe (away from pump) in the direction of going to the stove it gets warmer (not roasting) marked WARM.

Behind that is a second pipe from the Stove which is much hotter and goes straight up and then splits into the cylinder and also up into the attic. If any of this explains which is which.

To add, the pipes downstairs closer to the OF boiler are stone cold so don't think there is the issue with hot water generated from the stove going that way.

I have just added the original cylinder&oil boiler pipes (from your attachment, post 17) in my attachment, can you add where the hot cylinder pipe is on this attachment as well.
You won't really know if the stove water is going to the OF boiler until the pump kicks in.

henke · 08-04-2021 10:29pm

John.G wrote: »

I have just added the original cylinder&oil boiler pipes (from your attachment, post 17) in my attachment, can you add where the hot cylinder pipe is on this attachment as well.
You won't really know if the stove water is going to the OF boiler until the pump kicks in.

Added another pic. The one you are referring to goes in at the bottom of the Cylinder with the pipe further right going in at the top.

Yeah your right about the pump. It has kicked in quite a while now and checking the pipes downstairs before they go outside to the OF Boiler one pipe is slightly warm up top as it travels horizontal. Both pipes on the vertical down the wall are cold though so don't know there is that is expected. I think the stove would need to be on a long time for hot water to get the OF Boiler.

John.G · 08-04-2021 10:44pm

Can you highlight the "pipe further along"

When the pump is running is the pipe+pump still cooler than the "hotter" one as I am a bit confused re circulation ie is the stove pump pumping into the bottom of the stove (return) or what and is the top cylinder pipe hotter or colder than the bottom one with pump on?

henke · 08-04-2021 11:13pm

John.G wrote: »

Can you highlight the "pipe further along"

When the pump is running is the pipe+pump still cooler than the "hotter" one as I am a bit confused re circulation ie is the stove pump pumping into the bottom of the stove (return) or what and is the top cylinder pipe hotter or colder than the bottom one with pump on?

Sorry probably not being clear at all. Right now the pump is hot and pipes either side of it are very hot. Hopefully this pic clears up some queries. Of both both pipes marked hot I would say the one coming from the pump might be marginally hotter but you wouldn't hold any for too long, and below that I have marked where the pipes are only lukewarm, these connecting to the OF boiler

John.G · 08-04-2021 11:36pm

Will have to leave it for now but if the stove pump is pumping from the stove flow then it is pumping into the cylinder return which is very unusual for a gravity system, be interesting to see hot/cold pipes with OF boiler only on. I think I can now see why your plumber is wondering if pump/nrv are correct way round as its just possible that the pump is pumping from the stove return.

henke · 09-04-2021 8:28am

John.G wrote: »

Will have to leave it for now but if the stove pump is pumping from the stove flow then it is pumping into the cylinder return which is very unusual for a gravity system, be interesting to see hot/cold pipes with OF boiler only on. I think I can now see why your plumber is wondering if pump/nrv are correct way round as its just possible that the pump is pumping from the stove return.

Appreciate the help. Yeah not sure what is going on. I would have rhou the pump wouldn't have worked if it was fitted the wrong way around. I would prefer to get the thing definitely done the right way. I just don't know was there a logic in doing it this way the first time or what could be the consequence. I presume wasted oil and the pump being used needlessly.

Dtp1979 · 09-04-2021 8:37am

That’s piped arseways. The original installer hadn’t a clue. If the plumber that’s looking at it is unsure, then he hasn’t a clue either. Get a new plumber

John.G · 09-04-2021 8:39am

henke wrote: »

Appreciate the help. Yeah not sure what is going on. I would have rhou the pump wouldn't have worked if it was fitted the wrong way around. I would prefer to get the thing definitely done the right way. I just don't know was there a logic in doing it this way the first time or what could be the consequence. I presume wasted oil and the pump being used needlessly.

A bit of waste of oil alright but a bit of patience will track down the problem/fix.

Which cylinder pipe feels the hotter with the OF boiler on?

henke · 09-04-2021 9:07am

Dtp1979 wrote: »

That’s piped arseways. The original installer hadn’t a clue. If the plumber that’s looking at it is unsure, then he hasn’t a clue either. Get a new plumber

Current plumber only looked at it a few mins and seemed sure it was it was the wrong way around.

henke · 09-04-2021 9:09am

John.G wrote: »

A bit of waste of oil alright but a bit of patience will track down the problem/fix.

Which cylinder pipe feels the hotter with the OF boiler on?

I might need to check this when everything is cold and on startup. The OF has been about an hour now and I'd say there was still warm water from last night. But right now everything is hot and the pump is kicking in again. The pipes heading down the OF boiler I marked as lukewarm last night are hot now as would expect as are the others pipes.

John.G · 09-04-2021 9:31am

What worries me a bit more than the pump/nrv possibly being the wrong way round is the possibility that the flap was removed from the NRV otherwise with the pump o/s the stove (gravity) hot water will rise and flow (properly) down through the cylinder coil but cannot return to the stove return unless the flap was removed, get your current plumber to have a good look at the whole system.

The pump will always come in (wrongly) with the pipe stat in this position even if the system is OK, there actually should be two coils in this cylinder, one for the stove and one from the OF boiler.

henke · 09-04-2021 10:32am

John.G wrote: »

What worries me a bit more than the pump/nrv possibly being the wrong way round is the possibility that the flap was removed from the NRV otherwise with the pump o/s the stove (gravity) hot water will rise and flow (properly) down through the cylinder coil but cannot return to the stove return unless the flap was removed, get your current plumber to have a good look at the whole system.

The pump will always come in (wrongly) with the pipe stat in this position even if the system is OK, there actually should be two coils in this cylinder, one for the stove and one from the OF boiler.

Thanks. Yeah I suppose the only way to know for sure is to get it looked at properly. Funnily never knew there was a problem with how the stove/stat was installed for years. It was recently I noticed I keep needing to bleed one particular radiator every few weeks. It is a new radiator and no problem with it. Plumber looked at hot press and noticed pump on with OF Boiler and thinks air could be getting sucked into the expansion tank or something to that effect. Does that make sense?? It was while looking he noted the potential issue with how things are plumbed in here

Also, and it might be a non issue. The lit stove can take a while to kick in the pump and warm the radiators. Would the stat placement have anything to do with that?

John.G · 09-04-2021 11:15am

With a perfectly installed system the pipe stat if installed on the flow and depending on its setting will generally start the pump sooner than if it is installed on the return close to the stove and shouldn't start it at all with OF on and stove off but will start it if installed where yours is as water circulates through the cylinder coil irrespective of which heating system is in service.

It looks to me as if the stove pump is pumping away from the stove return, through the cylinder return (and rads) and back through the cylinder flow (and rads) to the stove flow and downwards through the stove and back through the pump. Until the circ pump comes in then the flow will be the other way (with stove only on) but will reverse direction immediately the pump starts. It is certainly not, under any circumstances, supposed to be installed this way. I did see a neighbours OF system operating in reverse for 8/9 years until he asked me to have a look as the boiler very occasionally tripped out on the hi limit stat.

henke · 09-04-2021 11:35am

John.G wrote: »

With a perfectly installed system the pipe stat if installed on the flow and depending on its setting will generally start the pump sooner than if it is installed on the return close to the stove and shouldn't start it at all with OF on and stove off but will start it if installed where yours is as water circulates through the cylinder coil irrespective of which heating system is in service.

It looks to me as if the stove pump is pumping away from the stove return, through the cylinder return (and rads) and back through the cylinder flow (and rads) to the stove flow and downwards through the stove and back through the pump. Until the circ pump comes in then the flow will be the other way (with stove only on) but will reverse direction immediately the pump starts. It is certainly not, under any circumstances, supposed to be installed this way. I did see a neighbours OF system operating in reverse for 8/9 years until he asked me to have a look as the boiler very occasionally tripped out on the hi limit stat.

Thanks very much for the time you have taken to figure out what might be going on here. Would you have any idea if any of this could result in air getting sucked into the expansion tank or what he could have meant there?

I will get in touch with the plumber and ask him to look at this properly and try to get configured properly. I will report back on the outcome.

John.G · 09-04-2021 12:22pm

Yes, that could certainly result in air ingress.

henke · 09-04-2021 12:44pm

Appreciate all the responses John G. Will report back.

henke · 09-04-2021 8:34pm

I have the stove off tonight and the stat on the side of the stove set to 0. Side of stove doesn't seem warm this time and it doesn't look like the pump is kicking in either. Would that make sense? Just wondering is this a potential workaround until I get it sorted properly.

John.G · 09-04-2021 9:42pm

Are you sure?, setting the pump stat to 0C should mean its constantly running?.

Edit: Is this a different stat to the one on the cylinder return?.

henke · 09-04-2021 10:04pm

John.G wrote: »

Are you sure?, setting the pump stat to 0C should mean its constantly running?.

Edit: Is this a different stat to the one on the cylinder return?.

Yes returned the stat on the cylinder to 55 as it was before. Not the pump stat. Just the dial on the side of the stove which goes from 0 to 5 I had turned sown 0 could be wrong though it might have no effect unless the stove is lit. It's for controlling the burn rate. Was just an odd observation this evening and if effects hot water circulating through the stove. Stove was cold and pump stat in hot press wasn't kicking in this time.

Edit: looking into it it should only control air flow. Odd the stove is cold down the side today and the pump never kicked in. I'll need to get it looked at.

John.G · 09-04-2021 10:10pm

The 0 to 5 is a damper of some sort so are you saying that with the OF on (and stove off) that the pump isn't running at stat set point of 55C?. Are the cylinder flow and return pipes hot?.

henke · 09-04-2021 10:25pm

John.G wrote: »

The 0 to 5 is a damper of some sort so are you saying that with the OF on (and stove off) that the pump isn't running at stat set point of 55C?. Are the cylinder flow and return pipes hot?.

Yeah but I don't think the setting on the stove should have any impact think am off with that but for whatever reason hot water doesn't seem to have travelled down to it this time. The pipes to the right of the pump are hot and to the left of the pump the pipe is fairly warm but not as hot. I guess it's just not at 55 and not starting the pump although the OF was on quite a while. A lot less time yesterday activated the pump. Will put on OF for another while to see.

As a sidenote is 55 a typical temp for a stove pump. I guess putting it higher would help stop the OF activating it but you would be burning a lot of fuel in the stove to get the radiators warm, particularly with the unusual stat placement.

John.G · 09-04-2021 10:37pm

It depends on what the stat is measuring, if its the flow (hot) from the boiler 55c might be OK but if its measuring the return it might be set to 40C. If you are not lighting the stove then suggest setting it to 65C or so but reduce it if lighting the stove.

henke · 09-04-2021 10:44pm

Funnily enough I recall the stat was originally set to 75 (maybe to avoid the problem with the OF boiler) and I was told it was too high I'd be burning too much coal to get my radiators hot. Might explain why it was so high before.

John.G · 10-04-2021 8:27am

If the stat is set too high then there is a danger of the water boiling in the stove as its temperature can be substantially higher than the temperature at the until the pump cuts in, so 75C might be the prudent max temp to set to, if the OF boiler stat is currently set to 65/70C then the stove pump cannot start at 75C. (until the stove is lit).

henke · 10-04-2021 10:06am

John.G wrote: »

If the stat is set too high then there is a danger of the water boiling in the stove as its temperature can be substantially higher than the temperature at the until the pump cuts in, so 75C might be the prudent max temp to set to, if the OF boiler stat is currently set to 65/70C then the stove pump cannot start at 75C. (until the stove is lit).

Ok think I'll leave the pump stat high at the minute when OF only is on so as not to activate it and will drop it down to 55 when only stove is on until I get it looked at.

Is this pump fitted the wrong way around?

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