# heating pump



## computerman (21 Jan 2009)

Should a heating pump be on the flow or return?

Anyone I ask tells me it should be on the return, but the english books show it on the flow.


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## DavyJones (21 Jan 2009)

IT doesn't really matter as long as it is decided at the design stage. Some say the pump lasts longer when on return as temp isn't as high.  On a vented system position of pump , cold feed and expansion is important as evrything infront of the pump is under positive pressure and everything behind is in negitive pressure. You don't want a situation where the pump is driving water up the expansion pipe.

Sealed system have fairly equal pressure all round.


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## computerman (21 Jan 2009)

Thanks DJ. Can I ask you another question? (I'll have a go anyway)

I have put a pressure guage on my boiler (I think the last owners of the house removed the old one) but I am getting a zero read.  I have checked for leaks, replaced old outside gunbarrell with new qualplex, (took last three days to dig trence etc snow rain ,.....) replaced pump with a unit 6. Put a non return valve on expansion pipe from F/E tank. Re balanced rads, bled pump, replaced safety valve.

Am no longer getting air in the system, (although its only 24 hours) but still no pressure.

I think my last option is to seal the system and see what way it plays. I have been reluctant to do this as it may cause more problems than it my solve.

What would your advice be?
thanks


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## DavyJones (21 Jan 2009)

ok.

First thing, remove NRV from expansion pipe. It will do nothing for you and will cause problems if it sticks. I.E it is dangerous and a big no no.

Things to remember are that 1 bar pressure = 10 metre head. How high is F/E tank from top of boiler. this will determine pressure on gauge. On a vented system, you should be getting about 1/2 bar reading on the gauge. Again this depends on position of tank in relation to position of gauge, Don't worry too much about pressure for the moment.

Do you think you have a leak?

If you seal the system, it will only leak faster due to higher pressure.

Try this first.

Tie up ballcock in F/E tank and leave it for a week, observe water level over this time. If it drops alot, then you have a leak.


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## noelf (21 Jan 2009)

DavyJones said:


> ok.
> 
> First thing, remove NRV from expansion pipe. It will do nothing for you and will cause problems if it sticks. I.E it is dangerous and a big no no.
> 
> ...


 

Have to say *I have never seen you give bad advice*, but you are always here do you ever go to work....lol


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## computerman (21 Jan 2009)

We moved into this house 6 years ago. We have a wellin the garden 4 water with hard water. previous owner never bought salt for the treatment system so whole house was seized. (surveyor never found it).

Had to replace immersion 3 times, 2 tritons, kettles ......

Before i moved here I would not have known one end of a screw driver from another.  But we live in the country and no one will travel out this far.

From day one we had to bleed the rad in my bedroom on a monthly basis.
There was never a pressure guage on the boiler, however a small (2 inch piece of qualplex from flow to a pressure release valve was in situe) This told me that there must have been a problem before.

In the meantime, I built (on my own) a 950 sq ft extension. I added 2 double rads to the downstairs. I rebalanced all the rads. But Im still getting air. After all the work over the last few days I think the air is gone but i will watch it over the next couple of days.

Personally I now think the boiler is too small, I have 25 rads. 

How high is F/E tank from top of boiler  in the attic of 2 floor house

I dont think i still have a leak........not sure. 100%.

When we moved in first the water in the f/e was hot so i put in a non return valve.

I will tie up the b/cock to night. and i will replace the preasure guage tomorrow - although its new, it might be broken.  

When I was working on the system, i did it on the fly, the water hit the roof of the shed before i capped it, so may be its the guage.

At this stage, God only knows.... sorry for the rambling!!


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## noelf (21 Jan 2009)

What kind of heat source are you using? Boiler or range?


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## DavyJones (21 Jan 2009)

computerman said:


> When I was working on the system, i did it on the fly, the water hit the roof of the shed before i capped it, so may be its the guage.



Ha ha, good man. You know your a pro when you attempt that kind of thing.

What size is the boiler?

it would be common for a vented system not to have a pressure gauge.

The size of the boiler would not cause air to enter system. Have you looked at the automatic air vent? they are cheap and maybe worth replacing. 

is the cold feed tee'd into expansion pipe? I assume not since you put on a NRV.


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## computerman (21 Jan 2009)

DavyJones said:


> Ha ha, good man. You know your a pro when you attempt that kind of thing.      As my father in law once said "To the uninitiated  -  a teaspoon of water is Niagara Falls!"
> 
> What size is the boiler?  Im not sure, its an Italian make that Ive never heard of.  I will check it again tomorrow.
> 
> ...


 
Ive just tied up the b/cock so its probably a waiting game.

My head is wrecked


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## computerman (22 Jan 2009)

Sorry noelf, just saw your message, its a oil boiler


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## noelf (23 Jan 2009)

Then it does not matter once its pumping in the correct direction.

Ret on the bottom and flow on the top.

Open vent system the vent/expansion should be on the flow and the cold feed inverted on ret.

Try a pressure test on the system and then when you sort things out keep it a sealed system as they are more efficient that open vented systems and less grief once you get them right.


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## DavyJones (24 Jan 2009)

If you are getting hot water in your F/E tank it may be pitching or that the cold feed is tee'd infront of pump on return, and it may also contribute to air being pulled down the expansion pipe, hence air frequently in system.


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## computerman (25 Jan 2009)

I checked the f/e tank yeasteray morning and water is being lost somewhere. (not much)

I think a pressure test my show up something. I am reluctant to seal the system as this my put already corroded connections / pipes under too much pressure.

The tank is not pitching and there is no tee on the cold return.

I will bypass the nrv with a straight connection and see it the hot water is still blowing back.  I put the nrv on 4/5 years ago.

On a positive note since last wed, I have had no air in the system!

I found small leak on old fitting around pressure release valve
I found 1 rad (double) leaking with water going under raised timber floor
I found a loose (not sure if it was leaking as ground was wet) union on 1inch pipe outside.

I'll keep you posted!


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## computerman (30 Jan 2009)

woke up this morning feeling blue
looked at the heating dont know what to do.

No water in upstairs rad
tells me system is still bad.

Just had a thought - could the cylinder that I bought,
be leaking inside the coil, causing the water not to boil?

Any advice would be nice!


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## DavyJones (30 Jan 2009)

computerman said:


> woke up this morning feeling blue
> looked at the heating dont know what to do.
> 
> No water in upstairs rad
> ...



Your a poet and you don't even know it!

I won't even try to give my advice in the form of a rhyme.

Two ways of telling if there is a hole in coil.

1: Your hot water may have a slight yellow tinge to it.

2: Because the two systems (plumbing and heating) are fed from seperate tanks , if they mix (through hole in cylinder) the water will try and find it's level, causing the tank that is lower to constantly over flow as it tries to reach level of higher tank. If the water level is exactly equal this won't happen.

tanks at exactly the same water level are rare.


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## dub_nerd (30 Jan 2009)

Sorry for piggy backing on this thread but I have a very similar problem. Underfloor heating on 2 floors, separate boiler house with oil-fired boiler, there is a pressure gauge in the hot press upstairs for the heating. I fill it to to about 3/4 bar, two days later it is close to zero. No obvious leaks inside the house or in the boiler house and yet this thing must be losing a fair amount of water. Where do I even begin to look?

In the meantime the upstairs underfloor is crocked, I believe the circulation pump probably burned out because it's water lubricated and water level upstairs disappears first. That's a whole other saga, because the original installer refuses to come back, even if I get the leak sorted, so I will be looking to repair that myself. Don't suppose anyone knows how/where to get Rehau parts?


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## DavyJones (30 Jan 2009)

Have you concrete and/or timber(joists) floors?

since you have not seen a leak, it is more than likely on the ground floor.

Is every room a zone? Does every room have it's own thermostat?

Have you checked all pressure relief valves? these sometimes let by.

I would suggest you do the following., each room that has UFH should come back to a manifold,. Isolate each zone/area one at a time and leave for a day or two. This will pin point where the leak is, or atleast what zone/room/area it is in. you must do it one zone at a time. disconnect loop from system if needs be.

The loop/zone should be one continous pipe with no fittings so,
I would start with hall ways I.E where the stairs has been fitted, to fit stairs they must dig into floor. A good installer avoids placing pipes where the floor will be pierced. once hallway(s) are isolated and drop in pressure still occurs, I would then move on to bathrooms,ensuites, WC. Toilets are screwed into floor.

Basically start wherever the floor was drilled.

Once a zone is isolated and no drop is recorded, this will give you a starting point for your search.

Good luck.


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## dub_nerd (31 Jan 2009)

All concrete floors. Every room is a zone and has its own thermostat. (Larger sitting room is two zones on a single thermostat). As it happens, upstairs heating has been knackered since last winter, so it hasn't been on at all. Mostly I am only heating three rooms downstairs... and I only live here at weekends so it's off during the week. Pressure drops during the week even when the heating isn't on, but I guess that doesn't tell me anything? How do I isolate the zones ... under each actuator at the manifold there is a thingy I can turn with a pliers and lock down, but these are on the returns not the flows, so I guess this is not doing what I need?

Btw, although the heating has been a disaster since the house was built 5 years ago -- something different has gone wrong every winter -- this particular problem is new ( ... since last winter ... I've been a bit slow off the mark fixing it). So I don't think its due to any original or recent drilling.

Because I'm away all week, I reckon I can isolate the upstairs and downstairs manifolds completely using the taps on either side of the flow and return, to confirm if its anything to do with the underfloor or something else. Ta for the advice. Back next week.


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