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Post by jcplumb on Jul 13, 2019 22:09:34 GMT
Had a call out tis week for a lettings agency I work for. Couple of radiators getting hot when control is set to water only. Thought it's 99% gonna be a zone valve failure. Gets there and no zone valves, just this Grundfos pump plan twin pump, looks like the feed from the boiler comes in from below then the heating has its own pump and the HW has its own pump. Like a Y plan where the twin pump does the job that the zone valve would normally do. Attachment DeletedAnyone any experience of these? I'm guessing there's a built in valve that closes when the circuit (to cylinder or rads) isn't calling for heat, or maybe just the fact the pump isn't spinning is supposed to stop the flow on that side?? would be a nice and easy job if it was a zone valve but this is a bit of a head scratcher for me. |
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Post by jcplumb on Jul 13, 2019 22:14:12 GMT
The pipe coming from underneath is the flow from the boiler.
The 15mm going up just leads to a bleed valve, right goes into cylinder coil, left to rad circuit.
Seems a bit like a solution to a problem that doesn't exist imo.
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Post by tomplum on Jul 13, 2019 22:40:28 GMT
funny un that Joe, I've never seen owt like that, I'm wondering is it a heat bank ? I can't tell from the photo but the clue will be, is it a fortic type cylinder,  |
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Post by crowsfoot on Jul 14, 2019 6:52:01 GMT
Back in the day I worked for a heating firm where we fitted a lot of gas board "guaranteed warmth" systems (SMC twin pumps) which was indeed a twin pump system with one for the heating one for the hot water - each pump controlled by room stat/ cylinder stat.
They worked very well and the first pumped primaries that I'd ever come across (just 15mm pipe was all that was needed).
The firm I worked for made them their signiture system to push because early MVs where devils for sticking which gave us a lot of call-backs.
It didn't catch really catch on nationwide though.
Interestingly the house where I now live had one of these systems installed when we moved in.
This Grundfos system looks to me like a new attempt of this now rather old idea.
It all works fine and was a top performing system and easy to install it disserved to "catch on"!!
Tappy,
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Post by jcplumb on Jul 14, 2019 12:23:41 GMT
funny un that Joe, I've never seen owt like that, I'm wondering is it a heat bank ? I can't tell from the photo but the clue will be, is it a fortic type cylinder,  Pretty sure it's not a heat bank, and it's not a fortic. It's a new lettings agency I've been doing some work for, they pay when the tenant pays the rent which can be nearly a month after I've done the job and they want a quote for every job so every job is 2 visits even if it's just a tap washer, so I'm not too fussed if they get a different plumber in. I've told them they need a heating engineer with experience of this type of system and it's not something for me. |
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Post by battle1066 on Jul 14, 2019 16:59:50 GMT
I've not seen that set up before.
However, since the system is Y plan and calling for hot water only and the hot tank (stored water) is upto temperature if the rad valves are open or TRV is on max I've experienced the rads getting warm to hot due to convection current (hot to cold) source thermal movements before - cure just close the TRVs down and fault disappears.
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Post by woodbine66 on Jul 14, 2019 18:22:56 GMT
Wasn't a twin pump set up called a G Plan? No, nothing to do with furniture. Not seen many in this neck of the woods, but as above, they seemed more popular in certain areas. Not sure how they prevent circulation going to wrong parts on these systems. Wonder if a pump that wasn't powered would stop flow going through it?
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Post by jcplumb on Jul 14, 2019 21:38:29 GMT
Wasn't a twin pump set up called a G Plan? No, nothing to do with furniture. Not seen many in this neck of the woods, but as above, they seemed more popular in certain areas. Not sure how they prevent circulation going to wrong parts on these systems. Wonder if a pump that wasn't powered would stop flow going through it? That was one of my thoughts, maybe the pumps are designed so that when not powered up they don't allow water to pass. I seem to get a lot of these types of jobs, I must be third on the list and the first two plumbers didn't want to know  |
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Post by crowsfoot on Jul 14, 2019 22:19:26 GMT
A "flap" type of non return valve was supplied with these old twin pump SMC systems for this reason. Perhaps it's not got one on or it's sticking? If I'm remembering right it was something like this (also the pumped flow for the h/w pump was taken off the top of the pump which was specially designed). Attachment Deletedwww.amazon.co.uk/Swing-Clack-Non-Return-One-Way-Valves |
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Post by dickpuller on Jul 15, 2019 7:03:15 GMT
A Pump Plan system while not common was a fairly simple alternative to zone valves as stated by my learned friend.
Simple enough, room stat calls for heat & CH pump comes on.
The HW may not have a cylinder thermostat, controlled only by the boiler Thermostat.
If it’s on a couple of rads getting slightly warm, it maybe heat migration from the Return. Check the ‘3 Ts’ rule has been complied with?
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